I've had this crash twice in the past couple weeks. At least, the first one was 03b--not sure if it was win32k.sys, or a system service exception.
I keep my computer on 24x7. I have installed the latest updates from MS.
The first time I was playing Diablo 3. The screen went black and then came back several times over an hour or so. I believe I had quit out of the game entirely, and was maybe opening Chrome, when I got the crash.
The second time a video I was watching with VLC media player just finished, and full screen was going back to windowed mode.
I realize the screen going black most likely indicates a problem with the video card or driver, but it is possible that is a separate issue--I also use the HDMI output on my video card to watch movies and listen to music on my home theater system, and I often see the picture go out and come back there, as well. However, it is only recently that I've seen it happen on my main monitor.
I am overclocking almost all my components, but have had this overclock work stably for 2 years or so now. (Core i7 920 overclocked to 3.9 GHz, video cards (2 GTX 460 1GB cards) overclocked as well, but not terribly much.) The system is stable in all games that I've played, and in various stress tests. I've run memory tests at various points with no errors found, though not recently.
I did recently install beta drivers for my video card as recommended for playing guild was 2, as the latest release drivers aren't working properly with it.
I also installed AVG somewhat recently, to augment Microsoft Security Essentials.
Dumps from both crashes attached.