Why Won't Software Run on Opposite Partition?

I wanted to understand why a program wouldn't run on the next partition. Let me explain a bit further then please answer why not this is going on. Out of many great reasons I have 2 partitions on my hard drive. I was signed in under my account on drive "D". When I was working in drive C, the need to run "Kai's Power Goo" came to mind. (This has the XP fix) Both accounts have Full Admin rights by the way. So I went to My Computer then to drive D and found Kai's Power Goo Program Files folder. It gave me some error- that I can not recall. However- with this in mind I have done this also with other programs that required serial/registration numbers.

What happens is the program will open as UNREGISTERED. I can usually enter the correct information and still not be able to run in Full Version mode. KPG is a retail version of its kind and uses no key or serial. Now I actually FIXED this issue with the KPG to where it runs the same from the installer directory or from a external/partition drive. The error was a Direct X or some other type which was asking for a .DLL it doesn't actually require. So, out of a hunch I installed the extra set of DLLs from the category in need. Suddenly the error is now gone and KPG will run from any partition and of course its installed partition side.
So I added the Windows XP fix and UL it for all to use. I never explained the extra functions that it now has.

So my question(s) is?: Why does a program run in its UNREGISTERED MODE or not at all from the next partition? PLEASE- not only "why" but please explain How? Also I did not mention that this will happen either way in disregard to having one or 2 Operating Systems. Same being XP installed on drive C and simply a formatted D with files.:confused:

:cool: At a later date I will attempt to find my KPG cd. Where I will find the exact files that install with the OEM CD. Then I will share the DLLs that were added. From there we can come up with the final conclusion. Have a great day- :)