windows xp repair not working

I have windows xp home. It crashed last night and keeps rebooting. Went to bios, started with cd drive. I wanted to repair so I did'nt lose my stuff. But after it gets to product code and I put in in correctly. It continues to start the process over. Is there anything I can do without removing hard drive and backing up files? thanks

 

How was it crashed? Or more accurately, what did you do right before that?
Did you install a new driver?

Have you tried booting in Safe Mode?
What does the setup program say before "starting the process over"?

 

I was just browsing on internet, shut down pc. When tried to start up it would only go to windows is starting page then reboot. Tried safe mode it won't let me do anything there either just continues to reboot. I tried restore to last known good config. No luck there either, thats why I figured I would just try the cd and repair. :cry