Locking internet connection to wireless while maintaining wired ethernet connection

We have 2 desktop PCs running Windows XP Professional Service Pack 3.

They are networked together with ethernet cables using the built in networking cards via a Dell PowerConnect 2716 gigabit ethernet switch. Nothing else apart from the 2 PCs is connected to the switch.

In our previous location a DSL modem also connected to the switch, and this was plugged in to our landline, giving the PCs internet access via the switch.

However we are currently in temporary accommodation in the basement of a shared office, and are unable to connect to the office's router/hub other than wirelessly.

The PCs (Dell OptiPlex 755s) don't have built in wireless, so we've connected a TP-LINK TL-WN725N 150Mbps Wireless N Nano USB Adapter to the first PC, and this gives us wireless internet access, connecting to the office's router/hub, but normally only if we unplug the ethernet cable from the back of the first PC.

Essentially what is happening is that when the cable is plugged in, the PC (wrongly) assumes that it should try to go online via the switch and not via the wireless adapter, resulting in no internet access, and error messages in Outlook 2007 (which we use for email) & in Google Chrome (which we use for accessing the web).

Someone else had a similar problem - see here:

questionhub dot com slash YahooAnswers slash 20081204172938AAGSPXI

and the only coherent answer (answer 6) enabled me to figure out what was going on.

The answer suggests running the Network Setup Wizard, telling the PC to use the wireless adapter for internet, not the wired network.

Doing this only partially works. If we restart the PCs for example (we have to at least every morning as we're required to shut them down every evening before we leave) and the ethernet cable is plugged in, the PC always switches back to trying to access the internet via the switch, not the USB adapter.

The only way to ensure the PC accesses the internet via the USB adapter is to unplug the ethernet cable, and then run the Network Setup Wizard, but doing so means we can't share files between the PCs via the switch (which we need to) and the 2nd PC can't run our job management software (as it needs to connect to the server applet running on the first PC to do so).

Also, running the Network Setup Wizard is infuriating, forcing the user through a series of patronising, condescending questions (treating the user as though they're an idiot, as with all "wizards") yet also giving overly complex options to choose from, none of which apply in our situation, and not giving an option to manually select the appropriate setup. It's breathtakingly badly designed from a Human Computer Interface perspective. Typical Microsoft.

Anyway, surely there must be a way to manually tell the PC to always use the USB adapter for internet access, even if it detects the ethernet cable, and even after a restart, while still maintaining the wired network?

To change the default printer, you go Start -> Control Panel -> Printers and Faxes, then right click on the appropriate printer, and then click on "Set as Default Printer". The selected printer remains the default forever, even after a restart, no matter how many other printers are connected and are in use.

Why isn't internet access controlled like this?

If anyone has any solutions to this it would be greatly appreciated. If it means changing some obscure setting(s) via editing the Registry then so be it.

(Finally, please don't reply at all if your reply is going to be in the vein of the first 5 answers to the question on questionhub.com. As reply 6 said, "What a knuckleheaded, down-thumbed, bunch of Answers!" Couldn't have put it better myself. Suggestions along the lines of "why don't you do such & such instead?" suggesting we change our set up completely, buy new equipment, or similar aren't helpful at all. They just infuriate. We've no money to buy anything, and we're guests in the shared office. We're lucky they're letting us connect to their internet at all.)

Many thanks.

 

With great respect, your description is very rambling.

But from what I can glean, you have software installed in your machines that are expecting one set up and you need to use a different one.

The first place to start is Network Connections. This should list all your current connections. Find the one relating to ethernet and right click then disable.

Another option is to remove the installed networking devices, but reinstalling these can be tricky as XP tend to assume you are using a dial up connection.

Look in Device Manager and deleting all networking software. It will be more effective in Safe Mode.

If I may, how long will you be in your current accommodations? If it is only to be a short time, can you put up with it for now?

Third is just a thought.

Can you tell us how you get on?

 

I agree with Senior Member Jojo on the problems you are having,

My suggestion, and it is only a suggestion, nothing more.

A quick temporary "fix" which unfortunately cost a small amount. (about $15.00 Australian, I don't know how that converts to the Euro or Pound).

Seeing that your primary net connection to PC number 1 is wireless, I would do.

Disable the ethernet connection on both PC's, don't uninstall this. PC number 1 should (from your description) should still have it's wireless connection to the office/router hub.

Remove the ethernet cable from both PC's.

Purchase the cheapest wireless 802.11n/g wireless pickup you can. Realtek make some good ones and the cheapest here, as I said is $15.00 Australian.

Install the new wif-fi pickup to PC number 2 and set it's pickup of signal to the server/router in the office/basement. Should be the same as per the server/router number you used for PC number one.

I may be wrong (frequently am) but this may give you internet access (by wi-fi) for both PC's each independent of the other.

The downside, as you say, is spending much needed money.

I too use a "cheapie" Realtek wi-fi pickup on our PC number 2 and notice no delays or degradation in download/load speeds.

Just trying to find a viable solution for you the simplest and cheapest way possible.

Regards, Aunty Jack.

 

http://www.dell.com/support/home/us/en/19/product-support/product/optiplex-755/drivers

you can install wireless drivers in any dell, the above link is the dell driver download site for you optiplex, and if you insert your service tag number you will get the drivers specific to your pc.

 

Thanks for the replies so far.

Jojo – apologies if the description seemed rambling. When I communicate I always try to include as much pertinent information as I possibly can, as people not volunteering information is a pet hate of mine. I’m convinced that the entire world would function much more smoothly if everyone volunteered everything that might possibly be useful to know from the outset. I’d make a hopeless secret service agent then I guess...

The machines aren’t using one networking set up & we need to use a different one, rather we need both setups to work simultaneously. Wireless for internet access for PC 1, and the Ethernet cables via the switch for the 2 PCs to see each other & be able to send & receive files to one another.

Disabling the wired connection as you describe isn’t an option for that reason.

I’m not sure how long we’ll be in the temporary location to be honest. The business is up for sale, and any improvements, long term planning, or expenditure is on ice at the moment. The current owner (sensibly) doesn’t want to spend any money he doesn’t absolutely have to, especially as 2 separate interested parties are supposedly considering buying the business (according to area management).

Aunty Jack – I’m afraid what you suggested isn’t an option, and somewhat misses the point. We’re not looking to have both PCs (independently or otherwise) connected to the internet. We need PC 1 to connect to the internet (this has to be wirelessly) while simultaneously have it connected, via Ethernet & the switch, to PC 2.

Each PC needs to be able to access files that are stored on the other one, both using manual drag & drop, as well as automatically (e.g. page layout documents that “look” in a specific location for linked graphics contained in them – often on the other PC) so the Ethernet & switch wired network is a must.

Both hard drives are full to the gills, and about half of the page layout files & linked graphics are stored on one PC, and half on the other.

Additionally, as I said in my original post, the 2nd PC can't run our job management software unless it’s directly connected to the first via Ethernet, as it needs to connect to the server applet running on the first PC to do so.

A further (relatively) moot point is that PC 2 (my own PC) can’t connect to the internet at all. This is because of years of customers’ USB memory sticks / flash drives being inserted into the PC to print their documents, resulting in multiple malware infestation which culminated in August 2013 in all internet access stopping completely. This was despite always running up to date anti-virus software (originally Norton, then Avast, then latterly AVG).

Our local PC repair shop (which uses 7 different anti-malware programs) was able to remove all the malware, but the damage to the internet drivers in Windows couldn’t be repaired, despite attempts to reinstall the drivers manually. I was told that no one anti-malware program is sufficient to protect a PC from malware completely, and yet that with a “live” PC in active day to day use, it’s very difficult to run more than one anti-malware program concurrently, meaning protecting a working PC from potential threats from dozens of USB sticks from all over the world (students’ ones) is almost impossible.

Of course for years I’ve been saying that, like in similar environments where I’ve worked previously, there should be a separate PC solely for public access, which should be stripped down to the bare minimum (no unnecessary programs installed etc.) with access only allowed to the minimum necessary features & programs; it should be completely isolated on the network, and be regularly wiped & restored from a cloned hard drive image. My advice was ignored of course, and I’ve had to suffer 15 months & counting of no internet access on my PC as a result.

The PC repair shop said the only way to restore internet access on my PC would be to wipe the hard drive and reinstall everything from Windows onwards from scratch. This doesn’t even bare thinking about unfortunately.

We have CDs (somewhere in storage in another building) to restore each PC to its factory defaults, but enduring the download & reinstallation of 7 years of Windows updates (the PCs are from 2007), reinstalling & configuring all the applications, fonts, etc, as well as setting all the preferences and so on would be a Herculean task that I doubt I could accomplish successfully, even over many days.

The original owner of the business departed years ago, we’ve moved premises twice since, and I know for a fact that we don’t have a note of the serial numbers or activation codes that we’d need to reinstall Adobe Creative Suite 3, which is the main software I use. The software was legitimately purchased by the original business owner in 2007 (he assured me of this), and is “Activated” on my PC, but having researched how to reinstall CS3 after a hard drive wipe, it looks like in our scenario the software might not be able to be reactivated successfully.

It’s not merely the fact that we don’t have a note of the serial numbers / activation codes, but since the PC can’t (prior to its hard drive wipe) connect to the internet, we’ve no way of deactivating CS3, and from what I’ve read on Adobe forums etc. it seems that no prior deactivation along with no note of the activation code is a recipe for disaster. I came to the conclusion that we simply couldn’t take the risk of wiping the hard drive. If my Adobe CS3 stops working, the business can’t operate.

I didn’t mention in my original post that PC 2 can’t connect to the internet, as I didn’t think it was all that relevant, but, given Jojo’s post offering a method for connecting both PCs to the internet wirelessly, I feel I should have, and that my approach of always volunteering as much information as possible has been vindicated! If I’d rambled on further, and mentioned that PC 2 can’t connect to the internet, Jojo wouldn’t have had to go to the trouble of typing his/her suggestion, as he / she would have known it was a non starter!

Elizabeth23 – are you implying that the TP-LINK drivers & software are in some way deficient, and that swapping these for Dell ones may give a more reliable result? Bear in mind that there’s no built in wireless hardware in either PC.

A further complicating thing to consider is this. My original post was based on observing the situation that occurred all of last week, and I wrote the post first thing yesterday (Monday) morning. It’s now Tuesday morning, and the behaviour of the internet connection for most of yesterday was unlike anything that occurred previously, and to me is even more baffling.

Firstly, as of yesterday morning, simply unplugging the Ethernet cable from the back of PC 1 automatically restores internet access. Plugging it back in again stops internet access (but restores the PC1 – PC 2 network). No need to run the Network Setup Wizard to switch the internet back on each time. At least this is what happened for a few hours.

Later on yesterday, bizarrely, when I plugged the Ethernet cable back in, restoring the network, the internet kept on working on PC 1. Things were working perfectly as they should be! After a few hours though, and for maybe 45 minutes, Outlook was able to send & receive emails as normal, but Google Chrome refused to connect to the internet. The problem was affecting the web browser but not the email client. Then later on, Outlook stopped working as well. Unplugging the Ethernet cable then restored internet access to both Outlook & Chrome.

This morning things are back to the “either or” scenario of yesterday morning. Unplug the cable & the internet automatically works perfectly for Outlook & Chrome; plug it in again to link the 2 PCs and the internet stops.

Given yesterday’s period of both connections working fine for a while, then things suddenly flipping back to the usual either / or scenario of their own accord, 2 things occur to me.

Firstly, we now have that Hell of Hells, an intermittent fault. Secondly, it might be the case that the malware that completely destroyed PC 2’s ability to connect to the internet is progressively corroding PC 1, and that one day, possibly soon, it too will be unable to connect to the internet at all, Ethernet plugged in or not.

Given all of the above, I doubt to be honest if anyone reading this would be able to offer a solution to these problem(s) without physically being here & examining the set up. There are just too many variables, and diagnosing a problem remotely is inevitably an exercise in frustration, but if you’ve read this far then thanks all the same, and apologies for this post approaching the length of War & Peace.

It’s as much a cathartic exercise for me as it’s an appeal for advice, as I’m sure you’ll have figured out!

 

need to insure that each pc is clean first separately, do the following download and update while connected and then disconnect:

Download, install, update and do full scan with these free malware detection programs:

Malwarebytes Free (MBAM): http://www.malwarebytes.org/products/

SUPERAntiSpyware: (SAS): http://www.superantispyware.com/

Remove all found, reboot, and run again until scans run clean, these can be removed afterwards if you so choose. Run scans one at a time, please.
===============

1. did everything work before in the previous setup where you were located before??

2. I use a wireless router at work and installed it but use windows to connect wirelessly not the routers connection.

3. http://windows.microsoft.com/en-us/...1&v2h=win7tab1&v3h=winvistatab1&v4h=winxptab1

above is troubleshooting wired and wireless connections.

4. https://www.google.com/#q=troubleshoot+wireless+connection+in+xp

above is google search page for more troubleshooting

5. for me I would disconnect all, uninstall all wireless stuff, insure pc is clean, and then reinstall

6. I would have to have the service tag to see if a wireless driver is available for your pc, if it is a desktop then I believe that you are correct it is not inherent in the system, please read the thread below as it may be due to positioning of pc's:

http://superuser.com/questions/328080/how-to-connect-to-wireless-router-using-dell-optiplex-755

 

In my experience, intermittent faults on computers invariably indicate hardware problems.

Since you've had a recent move, I'd be looking at hardware components first. Modems for example, cables. sockets.

It may sound daft, but the easiest way to check is to wait till all is running well, then move one of these, give it a bit of a gentle shake.

I realise that intermittent faults are often described along the lines of Hell of Hells, but personally, I prefer these as they demonstrate where the problem actually is.

 

Elizabeth23 – thanks for the advice. I ran both malware detection programs on both PCs.

On my PC (PC2) which can’t connect to the internet, neither program detected anything (although neither was able to update itself prior to running). This doesn’t surprise me as the PC hasn’t been online since the local PC repair shop ran the 7 different anti-malware programs and apparently eradicated all the malware.

On PC 1, both programs (after updating themselves) found what, to my untrained eye, looked like minor problems, which they quarantined in each case. An extract from the log from Malwarebytes is below:

___________________________

Version: 2.00.3.1025
Malware Database: v2014.10.14.09
Rootkit Database: v2014.10.11.01
License: Free
Malware Protection: Disabled
Malicious Website Protection: Disabled
Self-protection: Disabled

OS: Windows XP Service Pack 3
CPU: x86
File System: NTFS
User: Grant Todd

Scan Type: Threat Scan
Result: Completed
Objects Scanned: 348535
Time Elapsed: 37 min, 52 sec

Memory: Enabled
Startup: Enabled
Filesystem: Enabled
Archives: Enabled
Rootkits: Enabled
Heuristics: Enabled
PUP: Enabled
PUM: Enabled

Processes: 0
(No malicious items detected)

Modules: 0
(No malicious items detected)

Registry Keys: 20
(entries removed here to contain my post within the 10000 character limit, and also as I'm forbidden to post links)

Registry Values: 3
(entries removed here to contain my post within the 10000 character limit, and also as I'm forbidden to post links)

Registry Data: 1
(entries removed here to contain my post within the 10000 character limit, and also as I'm forbidden to post links)

Folders: 5
(entries removed here to contain my post within the 10000 character limit, and also as I'm forbidden to post links)

Files: 21
(entries removed here to contain my post within the 10000 character limit, and also as I'm forbidden to post links)

Physical Sectors: 0
(No malicious items detected)

(end)
___________________________

Only 2 of the files were marked as Red rather than Amber, and from the names neither made alarm bells ring in my head, although I’m no expert of course.

This morning I tried to work my way through the Windows “Wired and wireless network problems” tutorial.

Most of the questions presume that no internet connection (or intranet connection) can be made, and solutions are offered for these scenarios, as opposed to the scenario we have.

One section did seem relevant though. The text is copied below:

___________________________

Make sure the correct network adapter is being used

Some computers might have multiple network adapters. For example, if you bought a new
desktop computer and during the purchase you upgraded to a different network adapter, you
most likely have an onboard network adapter (a network adapter built onto your computer's
motherboard) as well as a secondary network adapter inserted into an available slot in the
computer. You can verify this by looking for two network ports on the back of your
computer. (Network ports look like large phone jacks.) Laptops normally have just one
network port unless you’re using a USB network adapter.

To set the default network adapter

Click Start, click Control Panel, click Network and Internet Connections, and then click
Network Connections.

If multiple network adapters are installed, the default adapter will have a check mark and be
labeled "Default."

If the correct network adapter is listed as disabled, right-click it, and then click Enable.

If the wrong network adapter is listed as the default device, right-click the correct device,
and then click Set Default.

Close the networking window, and then test for a network connection.
___________________________

The crucial sentence here is the one that reads “If multiple network adapters are installed, the default adapter will have a check mark and be labeled "Default.".

In other words, Windows should, in fact, behave for networking the way it does for printers, with a "Default" option that can be explicitly selected.

On both PCs 1 & 2, there are no check marks anywhere, and no option to make a network connection a default. Perhaps this option doesn’t exist in Windows XP (only in newer editions of Windows?) or perhaps some fault/error in our installations or configurations of Windows prevents this option from appearing?

Further, no mention in the text is made of the ability to select a Default specifically for internet access, over and above a Default for networking in general. It’s this ability that I mentioned I was looking for in my original post. Presumably this doesn’t exist either in XP (or not even in newer versions of Windows)? It’s this facility that would in theory solve the problem.

If this facility existed, I could select the built in Ethernet adapter as the Default for networking (the intranet) and the wireless adaptor as the Default for internet access. Setting both Defaults would presumably lock them in place, maintaining the choices across restarts and shutdowns.
________

I also looked at your Google search link, although the results seem too non-specific to our situation.

One further complication is that for the last few days both PCs seem to freeze up for about 10 seconds at a time at random times, normally, but not exclusively, when working with emails in Outlook (2007). This can happen either when the Ethernet cable is connecting the PCs, or not.

Jojo – I’d have to disagree with your comments about intermittent faults being preferable to constant ones from a diagnosis point of view, although I’m thinking about decades of listening to car mechanics talk about engine faults etc., and my Father talking about similar things, rather than thinking specifically about PC issues.

Finally, it occurred to me that if we were able to plug in some sort of adaptor to the switch which would allow us to connect the wireless (USB) adapter to it, both networking and internet would be via the switch, as per in our previous premises, and this might solve the problem.

Of course I guess the wireless adapter has to connect directly to a PC in order for the drivers / software to be able to operate it, meaning connecting it via the switch wouldn’t be possible, even if an Ethernet to USB adapter existed?

 

https://support.microsoft.com/kb/306126?wa=wsignin1.0

you want the network setup in the control panel not network connections.

go through the above link and see if this will solve the problem.

 

Elizabeth23 – thanks for the link. I followed the steps, and to cut a long story short, the problem now seems to be solved!

However, it took several attempts, and for a while neither internet access on PC 1, nor the PC 1 to PC 2 Ethernet link worked.

The steps in the procedure you pointed me towards are designed to allow other PCs on an intranet to share the internet connection of a particular PC (PC 1 in this case) which has a direct internet connection.

Achieving this would be the ideal outcome for us, but due to the malware damage on PC 2, isn't possible.

What sharing PC 1's connection seems to have achieved though, is for its own connection to the internet to remain permanent (Chrome now works all the time as well as Outlook) even when the switch is plugged into it via Ethernet, and the intranet is operating normally.

Therefore we are now back to the (far from ideal, admittedly) situation that we were in prior to moving. A huge improvement over the last few weeks, so many thanks to all who read & contributed.

What's ironic though is that the procedure is designed to switch on internet access sharing (letting PCs 2, 3, 4, etc. use PC1's internet connection) which it couldn't achieve in this case, but it did stabilise PC1's own connection via the wireless adapter, even with the PC also connected via Ethernet to the switch.

In other words, we wanted to achieve outcome A, and ideally B as well. You provided the solution to outcome B. Invoking this solution achieved outcome A, but not outcome B. The procedure should in theory have no bearing on outcome A, yet it did.

On PC2, I now have 2 entries under "Network Connections". The first section within this Control Panel is titled "Internet Gateway", and the connection is labelled "Wireless Network Connection on GRANT" (GRANT being the name of PC 1).

The second section is titled "LAN or High-Speed Internet" and the connection is labelled "Local Area Connection" (the Ethernet connection via the switch).

Both of these connections have icons on the right of the taskbar. Right-clicking on the wireless one & clicking "Status" displays a box showing how long the connection has been active for, the speed (72.0 Mbps) and the number of packets of data sent & received both to and from "My Computer" (PC 2) and the "Internet Gateway" (PC 1).

The final twist in the tail is that very briefly, yesterday morning, when I first activated sharing on the wireless adaptor on PC 1, internet access on PC 2 was restored!

I was able to load one web page, and send one test email. A minute later, and internet access was gone.

Since then it's as though I now have 1 or 2% internet access, where before I had 0%. For example, the yellow Windows updates icon is permanently in the taskbar, but the download percentage is forever stuck at 0%.

For Windows to know that updates are available, it must have been able to connect to the internet in some primitive fashion, however briefly, right?

Throughout this process, I've seen little to make me take issue with the view expressed by the technician at the PC repair shop (which used 7 different anti-malware programs on PC 2) that the damage to the internet drivers in Windows can’t be repaired, despite attempts to reinstall the drivers manually, and that only a hard drive erase & Windows reinstall will restore them.

That fleeting web page load & successful email send yesterday though was a cruel reminder of how things should be, yet cannot be.

XP giveth, and XP taketh away...

 

go to network connections and right click and choose repair, note carefully which area it says it can not complete and post back here with info.

 

I forgot to mention yesterday that PC 1 was left running overnight, and on starting up PC 2, there was only a single entry under "Network Connections", titled "LAN or High-Speed Internet" with the "Local Area Connection" (the Ethernet connection via the switch) listed below it.

To get the 1st section to appear above it (titled "Internet Gateway", with the connection listed labelled "Wireless Network Connection on GRANT") I had to right click on "LAN or High-Speed Internet", click "Disable", stopping the Ethernet connection, then Enable it again.

The same thing occurred this morning, PC1 again having been left on overnight, and PC 2 having been shut down.

However, prior to disabling & re-enabling the Local Area Connection, limited internet access seemed to be present. An Oracle Java update appeared, which seemed to complete successfully, and I was able to update AVG (2013 version) with the latest definitions. AVG also wanted to update the program itself to the 2015 version, but attempting this caused an error to appear however.

Also, the Windows update icon in the taskbar was able to download 46 updates, which I then allowed installation of. Only one of the 46 failed.

During the Windows updates download, I disabled & re-enabled the Local Area Connection, to allow the "Internet Gateway" section to appear. The updates download restarted where it had left off.

During the Windows updates installation, which naturally took a very long time, I was able to launch Internet Explorer 8 (Chrome isn't installed on PC 2 at present) and access the web(!)

After the updates were installed, PC 2 required a restart. After this, it refused to connect to the network, citing "limited or no connectivity". After another restart this problem persisted. Restarting PC 1 seemed to make things worse. PC 1 crashed during the end of the restart process, forcing a hard reset, which made the PC reboot into some sort of safe mode. The desktop was white, with a "Restore Active Desktop" button near the top, which didn't respond to clicking. A second restart of PC 1 gave the same result, but I was able to click the "Restore Active Desktop" button.

There was no internet access on PC1 at this point, but re-enabling sharing on the wireless adapter restored access for some reason. This makes no sense as it shouldn't be necessary for PC 1 to share its wireless adapter for it to be able to use it itself...

Anyway, PC 2 downloaded a further 11 Windows updates, and again all installed bar one.

Once both PCs settled down after their restarts, everything started working again, and I mean everything. Internet access (web & email) has been constant on both PCs now for a few hours.

If things carry on working without problems for, say, the next week, then I'll consider that all my efforts have been worthwhile.

The frustrating thing though is that I can't point to one, single definitive thing that I did that got everything working. The single biggest breakthrough seemed to occur though when I first (and again today) enabled sharing on PC 1's wireless adapter.

I was going to right click on one (or both) of the Network Connections & select "Repair", as Elizabeth23 most recently advised, but in the end I didn't need to.

Incidentally, on PC 2, right clicking on "Wireless Network Connection on GRANT" doesn't offer a "Repair" option, however doing the same with "Local Area Connection" does, although as I said I didn't need to click it, and won't do unless problems reoccur, for fear of upsetting the apple cart.

If I don't post again, consider that things worked out happily ever after.

Finally, for anyone with similar problems who has skimmed through this very long thread hoping to quickly see the solution to the problem, I'd suggest following the instructions here:

https://support.microsoft.com/kb/306126

the key point being to enable sharing on the wireless adapter that's plugged into the PC with direct access to the internet.

Thanks again to all who have followed this thread, and in particular to Elizabeth23 for staying the course & providing the solution.

 

Okay will keep checking back, and run checkdisk with the /r parameter, any time after ungraceful shutdowns is an opportunity for data corruption, you may have to run twice, until no errors are found.

http://support.microsoft.com/kb/315265/en-us
How to perform checkdisk

if you do not have Recovery Console installed, then run from the start menu

go to start, run, type in cmd

in cmd type in chkdsk c: /r and press enter

type Y for yes and press enter

type exit and press enter

restart pc, allow checkdisk to finish and run again

this is a lengthy process depending on the size of your harddrive, the percentages will fluctuate, this is normal, you can view report in the event viewer.
go to start>run> and type in eventvwr.msc, click on the applications directory, and in the right hand panel choose winlogon.