If the aforementioned "ahem" version is a recent DL then that slowing down problem has been solved as well. The game shouldn't freeze. Check the load CPU/GPU temps.
Yes its the ahem version. Now it Works perfectly without physx :O and btw temperatures got upto 78*C while playing everything max at 1920 x1080 w/o physx.. raised fan speed to 70% now.
I play mirrors edge. High with physx 9800gtx+ and temps go to 60*C max. I do put fan speed up to 70% while playing games though.
Idle 40*C @ 50% fan speed.