....sigh. Click on Run... (under the start menu) and type in dxdiag.
If you give us the log file from that...we could glean some information...just proabably not enough.
Just make one thing clear to me. If You have Multiple hard drives, Which one is your operating system running off of.
if you only have one...did you check the other drive letters to see if it could be one of those? (I myself have a secondary hard drive called G, a recovery drive called D, and a main drive called C.)