Forums are mistaken then because I have nvidia and still have crashes (the CTD with the one error message popup I think is related to the mall scavange map), and I have sound looping that hard lock my machine (and sometimes spontaneously reboot) like you describe.
It could be that your problems are caused by ati and mine are caused by nvidia, but the simpler explaination is that its valves fault, since L4D1 and 2 are the ONLY games I have that hard crash or reboot my machine. And they definately aren't the most demanding games I've run either.
Sorry, misspoke. Other way around. I have the 8800GTS.
After I had a reboot on L4D2, I got mad and went and played DoD Source, which then did it as well. I saw other posts that said the problem migrated into other valve games (L4D1, TF2, DoD Source), which leads me to believe there is something in the code that is causing the problem.
I then uninstalled my vid card and let it install itself with drivers from 2007, and DoD is fine now. Haven't tried L4D2 yet.This comment was edited on Dec 2, 2009, 13:02.