I had the same problem. IT's apparently a flaw with the overlay gamma slider... I don't know of a fix right off, but I will say I beleive the newer drivers caused more problems than just that with my computer. Ask around, I think people still prefer older drivers. I'm running 6X.XX
Oh, one other thing I noticed... Once when I went to the advanced proporties, the video actually corrected itself without my adjusting anything. That could be a temp fix. I guess when it was loading the advanced featuers(you know how the monitor sometimes flickers a bit) I guess something kicked in...