first:
never shut off by the power button, if you do then checkdisk should be run.
since you have repeatedly shut down from the power button, there may be system corruption.
you should burn a cd with hirens boot cd and run checkdisk through hirens:
once it is booting okay we can work opn cleaning up your pc
Courtesy of Jose Ibarra
Make yourself a Hiren's Boot CD which you can download from here:
http://www.hirensbootcd.org/download/
The ZIP file is large, so the download will probably take a little while to complete bit it is worth it. Then unzip the download to extract the Hirens.BootCD.ISO file that will be used to create your new bootable CD.
Creating a bootable CD from a .ISO file is not the same as just copying the .ISO file to a blank CD. You have to use software that understands how to burn a .ISO file to a CD to create a bootable CD.
In the Hiren's ZIP file are the BurnToCD.cmd file that you can double click to launch it, but I have never used it and prefer to use ImgBurn.
If you need a free and easy CD burning software package, here is a popular free program:
http://www.imgburn.com/
When installing ImgBurn, DO NOT install anything from UniBlue or the Ask toolbar (never install the ASK toolbar for anything).
Here are some instructions for ImgBurn:
http://forum.imgburn.com/index.php?showtopic=61
It would be a good idea to test your new bootable CD on a computer that is working.
You may need to adjust the computer BIOS settings to use the CD ROM drive as the first boot device instead of the hard disk.
These adjustments are made before Windows tries to load. If you miss it, you will have to reboot the system again.
When booting on the Hiren's CD you will see a menu of options. Choose the Mini XP option. Then it will appear that Windows is being loaded and you will be presented with a desktop that has the look and feel of the Windows Explorer interface you are already used to using.
One way to check the disk for errors is to open My Computer and right click your afflicted drive and choose Properties, Tools, Error-checking, Check Now... put a check mark in both the boxes and then Start.
Sometimes that doesn't work, so you can also click Start, Run and in the box enter:
cmd
Click OK to open a Command Prompt window and enter the following command (assuming XP is installed on your C drive)
chkdsk c: /r
This disk checking can take a long time (perhaps several to many hours) depending on the size of the volume, the amount of data on the volume and what the disk checking finds to do.
Let chkdsk finish and correct any problems it might find.
Depending on the the speed of your system, the size of the volume, the amount of data on the volume and what chkdsk finds to do, it may take a long time for chkdsk with error correction to complete (several to many hours) or it may appear to be 'stuck'. Be patient. If the HDD light is still flashing, chkdsk is doing something so don't interrupt it. It will finish eventually one way or the other. Keep an eye on the percentage amount to be sure it is still making progress. It may even appear to go backwards sometimes.
You may have to run the chkdsk c: /r more than once.