Somehow, somewhere, there might be a corrupted system driver. Or just about anything.
I'm guessing one course of action to do: either try to restore the system using a restore point generated by System Restore:
http://www.microsoft.com/windowsxp/u...emrestore.mspx
http://www.microsoft.com/windowsxp/u...w_03may19.mspx
Or have some technician (or better yet, a trusted friend who knows computers) to remove your hard disk first and backup everything on it (burned to disk or copied to another hard disk for a while), before checking exactly what went wrong.
The last resort is to reformat that disk and reinstallation of the operating system and/or software that came with it, and restoration of backup data.