This is the worst installer I have seen out of Nvidia to date. It can completely booger up your system! Count yourself lucky if you got through installing this version just by running the routine.
First off, if you are using surround (either 2D or 3D), then turn all of that off before trying to run the installer. Second, don't bother trying to run it from a normal boot, but rather go into safe mode.
Boot into safe mode and use the Windows Control Panel to remove the Nvidia graphic driver. Then you should clean your system of the Nvidia Control Panel. This is an option of the DriverCleaner.net program, which is what I used. There are other cleaners out there and if you use one you might report back your success path if you find one. Finally, while still in Safe Mode install the 347.09 version. I recommend not installing GeForce Experience, but it's up to you. Reboot and all should be good.