I have had that error multiple times as well, but as it mines okay most of the time, I don't give it much thought myself. In scrypt mining that errors pops up when you have overclocked your card too much, but since my card is running stock when it gets that error, that probably isn't it.

But you mention getting tons of them. Does tons means so many that you can't mine normally? In that case there's something oddly wrong. But most of us will need more information to be able to help you. What card are you using? Is it overclocked? What OS, what driver?