Have you looked at this article :
[Only Registered and Activated Users Can See Links. Click Here To Register...] ? Maybe that may get you started on your issue. Mainly what it is telling you to do is to do the following.
First get out your Windows XP CD and stick it into your drive.
Second, whenever you get to the Welcome Screen, click "r" to go to repair mode.
Type in your Admin password, or if you don't have one set press "ENTER".
After doing that type chkdsk /r in the console.
See if that works out at all for you.
Rat