Is the problem only on your account? Sis ok? Are you using the built-in Administrator account? Or? Are you on a network?

One possibility: If your old profile is corrupted in some way, you can move the files and settings from the corrupt profile to a new profile.

Another: User Profile Hive Cleanup Service

Another: If you have the XP CD insert it & choose Exit from the Menu (but leave it in the drive)
Then go to: start | run | sfc /scannow