If your system isn't too screwed up and you can get to a command prompt, formatting your hard drive should solve things, and once you're back up, you should have no problems with this.
If a format doesn't solve it, you may have a bad power supply or motherboard, so try replacing them one at a time until the problem goes away.
Worst case scenario is that you'll have to switch out your video card or monitor, but I doubt it'll get to the monitor stage...the video card is usually the final straw that kicks everything into gear if it hasn't worked up to that point.
Good luck with all this. Hopefully you are able to use all these suggestions today, I heard NewEgg's prices are going to increase April 2nd