Open Question: Monitor glitching at startup?

Whenever I boot the computer (or the monitor, if left off for a while), the screen will fade out to white and then shut off altogether. The only solution I've found is turning it on and off and etc until it fades out to invert the screen I have, then it'll glitch out into the normal screen. This started about two weeks ago, and I have no idea what it might be. I recently scanned for viruses and got rid of most of them, I think. Also, I'm running Windows Vista.