After doing some more tests of my own, I'm convinced that this is a driver issue. This kind of thing is common when a company releases a new GPU and CPU in the same model. (In this case the 6750M and Sandy Bridge i7) Correct me if I'm wrong, but each of you have either the top spec 15" or the 17" model, yes? By now, I guarantee Apple is aware of the issue, and I would expect to see a driver update by, if not before, 10.6.7 is released. Hold tight, my friends. Returning your computer or getting it replaced isn't going to fix this, and neither is complaining to Apple Tech Support (other than that it will make them more aware of the issue). The tech people you talk to have no direct interaction with the software engineers, and aren't going to be able to do anything. They may even recommend useless troubleshooting steps like an OS reinstall. I think we'll see resolution of this once they release a software update, and not before. I've given a link to this thread to a senior level tech advisor at AppleCare, so continue posting your reports here and they will be forwarded to the engineers. Being specific about situation, peripherals, programs, and timing will help them immensely, comments such as "THIS IS BROKEN, FIX IT" are less helpful. Cheers.