Kind of derailing the thread, but Flogger23m, I had what sounds like the same problem as you. I had an install that apparently went fubar. No matter what I did, it seemed I could not change my driver.
What you may have to do is:
- Uninstall your current drivers as best you can
- Then set your graphics to VGA.
- Close Windows.
- Restart the computer
- boot Windows in "Safe Mode".
Try uninstalling again, then run DriverSweeper found over at guru3d. While your at it re-run crap cleaner, clean the registry and delete any and all folders/files of nVidia.
The key for me was switching to VGA and then booting in Safe Mode to tidy up.