I'm so lost on what to do with my computer.

I turned it off for a storm last night (I usually leave it on for days at a time, though that's likely to be a big mistake) and when I went to turn it on this morning, it didn't quite work. It reaches the Windows XP loading screen, then returns to the beginning of its boot. It's stuck in a cycle.

I left it alone, hoping that maybe it would work itself out, and all that it managed to do was reboot itself for two hours straight. I've turned it off several times, and it only does the same thing. Is there anything I can do to stop this madness?