I also should have mentioned trying a System Restore.
System Restore
--------------------------------------------------
You might try a System Restore to a point prior to your problem:
start > All Programs > Accessories > System Tools > System Restore
If still no go try making a new account and transferring your data as seen here:
How to copy data from a corrupted user profile to a new profile in Windows XP
Other ideas perhaps in this Google although many suggest a Repair Install which at this point in time would be considered an extreme measure.
active desktop recovery - Google Search