Windows Failed to Start?

So this morning when I attempted to turn on my computer I was given a screen that said "Windows failed to start" something about a software or hardware change or losing power during start up. It then gives me the options of "Launch Start Up Repair" or "Start Windows Normally". Regardless of which one I choose it brings me to the loading screen and after about 3 or 4 seconds the whole things just shuts down. I haven’t recently done anything to my computer, at least not that I know of, and I have never experienced this problem before. The computer won’t even stay ON. Why did this happen and how (if I can) do I fix it?

i’m running Windows XP on my Toshiba.

After 2.5 years, my Dell XPS has become too slow. I use all of the spyware (Ewido, AdAware, and Spybot) and virus apps. (E Trust Internet Security Sutie) and have never had a virus. I use CleanUp! and WindowWasher and Registy Mechanic to no avail. I think the registry has simply gotten too huge. It is time to do a clean install of XP Pro.

1. If I didn’t know better I’d say that you were________
2. When you’re going through hell, don’t ______________
3. If I was stuck in an elevator with Paris Hilton I would ______.
4. Whenever I think about you I want to ________.
5. I I was president the first thing I would do is ______.
6. If I met Sunshine?MattBaby I would ask her ____________