kashm,
I'd bet my right testicle that you have some sort of malware, virus or worm that has corrupted your registry. If you had a "good" registry backup, I'd advise you to repair your registry with the backup.

Take a look at the following:

http://support.microsoft.com/kb/307545


But before doing that, I'd run two or three different antivirus scans (online and hard drive based scans).

I'd then take a look at the following:
http://www.techzonez.com/forums/showthread.php?t=9739

Make sure your system is clean. Run hijack this, scan with AVAST, NOD32, Lavasoft, Spybot Search and Destroy etc... and definitely rule out any viral, spyware or other malware activity that might be creeping in on your system.

If after all that no virus is found, then I'd attempt a registry fix as stated in the first couple of lines above.

If none of that worked, I'd first try a system restore (doubt it will solve this problem, but who knows).

If that failed, I'd try repairing files with the "SFC /SCannow" repair method that finds and replaces any windows files that may have become corrupted.

If that didn't work, I'd then backup all my files that are of importance, and run a repair install:
http://www.michaelstevenstech.com/XPrepairinstall.htm

If the repair install fails to fix the problem, then I'd take the drastic step of reinstalling windows XP from a format/freshly.

http://www.winsupersite.com/showcase...p_sg_clean.asp

Hope that helps.