Your post is not going to read by all with such a title. Consider it top priority to craft a TITLE with something that conveys the problem so people will look at it and think "I can help."

Since XP has fallen down and can't get up, before you start into repairing the OS, try things like:

1. Unplug USB devices.
2. Remove the case cover.
3. Remove a recent memory addition or other new device.
4. Consider getting KNOPPIX CD to help save your files you can't lose to CDR or CDRW media like you read at http://tips.oncomputers.info/archives2004/0401/2004-Jan-11.htm
5. Tell a longer story about your machine, recently loaded software (KAZAA?) or other.

Bob