You OS might be corrupted at this point. I read that you did a repair, is that correct? Did you put the XP CD and boot your computer with it and then when Windows XP ask you to full install, you selected yes? From there, XP asked if you want to do a repair and you select yes?
Before you do this (but it might save time if you do a repair first), back up all data important to you and do the following... it might help. (By the way, you shouldn't loose anything by repairing the OS, but just in case save important files).
Get these programs:
Process Explorer
HiJack This
Object Desktop Drive Scan
Spybot Search And Destroy
Microsoft Defender Anit Virus
Boot in safe mode.
Run these utilities from the START >> RUN box:
services.msc
msconfig.exe
regedit
Any setting, folders, names that look odd, check them out. Check them from from automatically starting up, make sure windows messenger is disabled (in the services.msc app).
Run HijackThis
Again, any names, entries or what have you that look odd, make a note of it.
Run Stardock Drive Scan and see any wierd looking folder names... then delete them (or rename them). The ones that DON'T allow you to are the prime suspects
Run Process Explorer:
This should tell you every process that is running on your computer. Sometimes these virii have 2 (two) proceses that basically restarts the other proces if you delete or end the other process. So you actually would have to stop BOTH.
ONCE YOU HAVE YOUR LIST OF CRAZY NAMES, DELETE THEM. Delete them from HiJack This, delete them from regedit (also use regedt but deleting will be done in regedit). You might have to actually stop (not delete, just stop from the seervices window or from Process explorer) a microsoft svhost in order to delete the alien process but leave that as a last hope.
Now run Spybot and delete some more
Now run MS anti spyware and remove whatever else
Now run one anti virus software (do not have 2 or more anit virus software platforms installed at one time)
If your system still isn't running properly, repair it with the XP boot CD again.