A similar problem existed with Sherlock Holmes Nemesis and Physx drivers. You can read about it here.
They suggest downloading the latest drivers which provide the capability to remove the drivers and there's also a link to older drivers version 9.09.1112. These drivers worked for me, but I did uninstall the existing one before installing the 9.09.1112. I don't remember how the first driver was listed, but the 9.09.1112 version is listed under NVIDIA PhysX in Programs and Features (Win 7's version of Add/Remove Programs).