I recently added my Sapphire OC 7970 with 12.4 Drivers. I had a problem with the desktop showing up under a couple of different conditions and was forced to restart. A couple of times I've seen this during boot. I have not ever seen this once the OS is going.
Is this a driver problem? I disabled ULPS and haven't had an issue, but it's only been a few hours. This looks like it may be an easily-identified problem.
Have you guys had this happen before?