. . the only thing you can probably do is reinstall. First try a repair install.

1. Find your license code (should be on the sticker) and get it ready - you only get one try here.
2. Boot on the XP CD - you get the choice of Install or Repair, take "Install".
3. It will then find existing installations.
4. Select the existing installation and take R for repair at this point. It will then go through the reinstall.

If that doesn't work you'll have to do a full reinstall taking "Install" at the second question and reinstall all your software. If it says it can't find an existing installation (even though you know very well there is one because it boots and crashes), you'll have to do the full install no matter what. I don't know a way to get it to change its mind.

Of course there's the possibility you have a hardware problem. That's not often the problem in my experience, but sometimes it is. If the full reinstall doesn't work it probably is, but by then you have to reinstall all your software after fixing the hardware problem.

Others may have other suggestions.

. . generally to recover functionality after removing serious worms - it patches the wormholes, sometimes.