computer infinitely restarts

[Aerozord]

I am using windows XP

Weirdest thing is I did nothing out of the ordinary, I didn't visit any new sites or download anything new, in fact the last thing I was doing was playing new vegas when it froze calling for a restart. When it did restart I got the usual "windows restart" message asking for
"start windows normally"
"safe mode"
ect options.

Regardless of which I select it gets, at best to windows loading screen then it restarts itself displaying the same options. I cant think of any other option but to reformat, but hoping you guys might know of another option