Either 1 of 2 things I think may have done this
1) A hard drive sector error/failure

due to a voltage spike?
Run Scandisk to see if this is so

will display a message will try to correct by isolating that area (you may get everything back?

) if no joy, then try running "System Restore")
2nd possibility is that you have been hijacked

either by a Hacker or some form of scumware
Have to run a virus scan and a spyware detector to isolate this
My guess is #1 will be the more than likely culprit
XP is quite hard to crash. Takes something drastic to cause a prob like yours

BTW- I save my Favorites to
www.linkagogo.com I have well over a 1000+ saved there.It auto-arranges them into a personalised directory page

give the site a visit
If your computer goes down badly,the saved favorites are safe

(can access from anywhere

)