You don't have to uninstall the iz3d driver if you use it occasionally. Simply deactivate it in the control center. If it's activated by hotkey it means that it still hooks the game and renders stereo. It's just that separation is set to mono value. Deactivating disables the "hook".
Another way without uninstall: You can add a noncompatible application into the iz3d exception list. The driver will not hook the calls from any applications in the exceptionlist.
Mb: Asus P5W DH Deluxe
Cpu: C2D E6600
Gb: Nvidia 7900GT + 8800GTX
3D:100" passive projector polarized setup + 22" IZ3D