What version of Video Drivers do you have now? is it this one?... NVIDIA DRIVERS 301.42WHQL
What about Audio Drivers? have you installed the latest as well?... I see they are up to R2.70 Realtek
I am sure you know that you just can't install the newest drivers on top of the old ones, you must uninstall the drivers, uninstall the PhysX drivers as well, use the Nvidia removal tool if necessary, restart and then install the latest versions with Elevated Admin rights (I right click on the .exe file and Run as an Administrator).