Nothing but lockups for me

So I bought Black Ops for my PC about a month ago, because a couple of my friends were harassing me to no end to get it. The game is fairly fun (Zombies is awesome), but I've dealt with nothing but lockups whenever I do multiplayer online. And before anyone asks it, yes, my video card drivers are updated to the latest drivers. In fact, nearly all of my drivers are the latest greatest since I put Win 7 on it about two months ago. My system is more than capable of handling the game also, so it shouldn't be caused by my hardware (Phenom II 6-core, Radeon HD 5870, gskill ddr3 1600).

The lockups (when the game freezes) are random: it can happen two minutes into joining a game or it can happen 15 minutes into it. It even occurs at times when I'm just in the game menu and before I've joined a game (although this has maybe only happened two times). What is most frustrating is that the last time it happened I'd gotten a number of awards during a match (head-shots), and after I crashed I went back into the game and it didn't look like I'd actually been awarded my points nor gotten those awards since I'd crashed.

Has anyone else dealt with this game freezing on their PC? Any ideas on how to fix it? I tried posting on the black ops forums and all I got were a bunch of jerks telling me to buy the game for PS3 or XBox. That's not a solution. I just basically got screwed out of $59 if that is a solution. It's my first CoD game, and at this point it's looking like it'll be my last as well.

EDIT:
Forgot to mention – after BO2 locks up then I have to end task it to get rid of it. After having end-tasked it then my network connection is jacked up… and bad. I can't even get to the internet when it happens and I have to completely reboot my machine to fix the problem.