I've not done much research into the issue and it may be that someone else on another forum has already found a solution, it seems like a conflict between the driver and Windows Aero, or perhaps a problem with the cards idle power state.
Actually I had no issue today after you replied, then after playing BF3 for a bit, the issue returned. Even after letting the computer "rest" for a while, the issue remains. (which is when I then replied)
Also, the my card in particular is having graphical issues in a lot of intensive games, upping the voltage to 1.050v SEEMS to have fixed those graphical errors, but not this one in windows.
I bought the card just a week ago anyways, so I'm probably just going to RMA it (tigerdirect won't take a return on it, sadly) so I guess I'll see how that goes.