Homer: I have dual monitors and it's doing it on both of them, so I don't think that the monitors are at fault.
Brett: I just dusted out the video card, ATI Radeon 9800, 2 days ago so it should be pretty dust free. That seemed to have helped, but now it's worse than it was before. Originally it was just when I tried to play a game or do something that took up the whole screen, then I would restart and it would be OK. Then all of a sudden it started doing it all the times, sometimes worse than others.
p.s. Thanks for the very quick help so far