Regarding the CoD issue you experience, does it only happen @ 16x12?
IIRC it happens at 1600x1200 and above with any form of AA enabled, and it seems to get worse the higher the resolution you use (my screenshots used 1920x1440). If you have AA disabled the problem doesn't appear to happen.
It also happened on my 6800U + nForce3 system using drivers as old as 61.77.
There could potentially be some sort of issue with the driver using SSE2 & above math when the game was expecting 3dnow or SSE or FPU to be used.
This is certainly possible although I did disable enhanced CPU instructions in the driver and the problem still happened.
I was testing actual SoF gameplay yesterday with 16xAA and sure enough at odd times it would freeze up like it did in the cinematic and then unfroze shortly after.
I think both the CoD and SoF issue are related to a problem in the driver memory management routines. That is to say when you load the VRAM with AA in CoD or SSAA in SoF it exhibits the problem but not when running MSAA under SoF or disable AA under CoD. Clearly the latter settings are less taxing on the memory than the former.
As for the trigger, it could be something as simple as using the global profile for everything like I do.