I have the exact same problem.
When I first got BLOPS2 it ran flawless for about a month. Highly enjoyable game.
Then on March 29th it started freezing just minutes into the game and loud static would come across the speakers.
Occasionally I will get a screen like the one below:http://i44.photobucket.com/albums/f44/Rwayne/blops2crash.jpg
But it is kinda rare. I have only seen it come up 3 times. My computer has probably frozen at least 18 times by now.
I did a clean install of the drivers and I made it 4 games with out a crash before it started again. Also when I disable the sound it seems to work but what fun is that?
COD4 and the original blackops will crash too but not as frequently.
This is highly frustrating.
I thought it was an AMD Driver issue but apparently not since the OP is using a GeForce.