I have the same problem (nVidia GTX580, reference card with no over-clocking), I've noticed it happens more frequently during some map changes, e.g. docking at ESD, but it's also happened in some PvP's, or even leaving PvP,
the only thing that has changed my end since S6 has launched is the installation of the new nVidia drivers (which fixed a slight frame rate issue I was having), so I've also tried the new Beta drivers 304.79 which haven't made any difference,
I find it odd, how it's been fine up until S6, but I would also like to point out that S6 on tribble was fine and I played that a lot,
so in my case I suspect something isn't playing nice with these new nVidia drivers,
I'm afraid I can't give any dumps, nor crash reports, nor error logs, the most I can say is, in my case, the nvidia driver crashes, the client goes blank (black), my iTunes hangs for a few moments while the driver restarts etc, then I have to restart the game again despite being able to see the cursor. Each time, it's the same
Timeout detection: The Video Scheduler component of the Windows Vista graphics stack detects that the GPU is taking more than the permitted quantum time to execute the particular task and tries to preempt this particular task. The preempt operation has a "wait" timeout?the actual "TDR timeout." This step is thus the "timeout detection" phase of the process. The default timeout period in Windows Vista is 2 seconds. If the GPU cannot complete or preempt the current task within the TDR timeout, then the GPU is diagnosed as hung.
Preparation for recovery: The operating system informs the WDDM driver that a timeout has been detected and it must reset the GPU. The driver is told to stop accessing memory and should not access hardware after this time. The operating system and the WDDM driver collect hardware and other state information that could be useful for post-mortem diagnosis.
Desktop recovery: The operating system resets the appropriate state of the graphics stack. The Video Memory Manager component of the graphics stack purges all allocations from video memory. The WDDM driver resets the GPU hardware state. The graphics stack takes the final actions and restores the desktop to the responsive state. As mentioned earlier, some older DirectX applications may now render just black, and the user may be required to restart these applications. Well-written DirectX 9Ex and DirectX 10 applications that handle "Device Remove" continue to work correctly. The application must release and then recreate its Microsoft Direct3D device and all of its objects. DirectX application programmers can find more information in the Windows SDK.