My computer has also consistently has very similar crashes whenever I play a game, though this is the first time since my 6800 that the dialog box has appeared again. The video crashes in a way that can be seen on the attached image, a screenshot from World of Warcraft after a crash (it's low quality, but you can see how strange rectangles have been shifted in random directions...I can't really describe it). The sound oddly continues in a 5-10 second loop after the crash, though keyboard input is cut off.
This has happened many times, and I've constantly been trying to find a solution for it. At first Geeks to Go suggested it was overheating. However, a temperature monitor suggested that this was not the case. My local shop suggested that my PSU was underpowered, causing me to end up buying a new one. Didn't work. I really just want to be able to play games on my computer again without crashing (it's a $5000 Area 51 and I want my money's worth).
I ask that you please help me to the best of your ability. I have a feeling that this time, I might finally be able to get an answer as to what's going on. Thank you.