Best bet, however much of a pain it is, would be to reformat and start from scratch, install XP and then apply all the patches, up to SP2.
Windows is a house of cards. You have attempted to apply a sledge hammer fix to a house of cards with lots of evil drones in place of the necessary cards. Won't work.
It's actually a good thing, if this is what is happening, that your PC has blown up on you. God knows what those evil drones have been doing to you while resident on your PC.
Checked your credit rating lately?
I don't do "credit". I reckon I am screwed! If cash won't do it, BUAID NO BAS!