I hope these clues help narrow down the problem:

I can do anything else in the game w/o a problem, even host a TDM... but when I try to host a Co-op hunt, it runs at first... then a few people join, and after about 5 minutes, things lock up... the game is crashed. I use the windows button to exit and I see the following message/popup

"General Protection Fault"... and then the next line "History"... and then an 'okay' button below it. There is no info posted after history either... it only says that.

I have tried it multiple times, and end up with the same thing every time.

My specs: Intel i7 920, Asus Rampage 2 Gene mobo, OCZ XMP 6gb ddr3 1600, nvidia GTX285. All drivers are up to date as of last week when I f-disked windows and restarted from scratch.

Any ideas as to what the problem might be?

Thanks for any help.