I just bought a 7950 and I'm having this issue. It is only one one monitor of three, and varies on which monitor or output it is on. I've tried everything from re-seating the card to rolling back drivers and nothing fixes it.
file:///C:/Users/Wyered1/Downloads/IMG_20120506_220540.jpg
file:///C:/Users/Wyered1/Downloads/IMG_20120506_220540.jpg