Sure sounds like you need to get your data and reinstall

Borrow an XP CD (same version as yours, Home or Pro) and try XP repair.

You could pull the HD and put it in another PC then pull your personal data off, then reinstall.

Or

Download PE Builder and make a BartPE recovery CD to get your data.

Like rik said, lets us know what you decide and we'll keep trying to help.