yeah every time you update your vid drivers it's a good idea to do a little "dance" lol...first get a program like
DriverSweeper, install it but don't run it yet.
Un-install your drivers thru Win7 like normal (add/remove programs).
Reboot when it asks you; but go into safe mode.
Run DriverSweeper in safe mode and only select Nvidia - Display. Run the cleaner and reboot again back into normal Windows.
Install the new drivers, and reboot one more time when it asks you and you should be good.
It's a PITA; but this is the sure way to avoid conflicts