I'll check with my buddy who runs something similar to that. She had to reinstall though but wasn't entirely sure what had caused her similar issue. That card meets the very low end of the requirements for this game. It's Friday though so I more than likely won't be able to catch her until late tonight. Until then, you might want to try putting everyone on its absolutely lowest setting, restarting the game, and seeing if the issue continues. If it does, thent eh reinstall might be something to look at. If the issue goes away, then try uping the odd setting, applying it, and restarting the game if necessary for it to take in order to figure out what your GPU can handle.
I've been playing on the lowest settings since launch, and never had a problem until now.
That's partially why I thibnk it might have something to do with my ISP, I've switched from AT&T DSL to Mediacom Cable internet.
I've also switched from a 20 inch monitor to a 44 inch HDTV, but again, I'm not having any problems with anything else.