What are you doing when the error occurs? Anything that causes the game to lose focus will force this error. I've also heard of some issues with one of the Nvidia cards (GTX580 i think?) so I wonder if that's your case.

As a tech support rep will more than likely come in and ask you to provide a whole slew of information (the format is in a sticky at the top of these forums) you may as well do that now.