Not sure I've seen a checkbox for Clean Install and I'd definitely would have checked it. I've noticed that when you currently install new Nvidia Driver that it states it's uninstalling old driver -hope thats true and accurate. I've never had one issue with an Nvidia driver before but this situation got outta control quick.
At first I tried simply adding the ControlPanel folder from an older driver which had no effect. I then tried installing some my older drivers in backword sequntial order -everytime I attempted, I would get "Driver Installation Failed" with no further info. Worser still, it had stated it had successfully uninstalled previous driver -which left me in driver-less limbo.
I finally got an ancient driver from Windows Update to work for my 460's but as soon as that was fixed -my Network card driver mystreriously failed and I couldn't fix it via the Mobo utility disk -no internet.
Seems like something went awry in my Registry so I was forced (after a few Reg integrity programs) to wipe the HD clean nd reinstall Windows fresh.
Kinda ironic after a night of drooling over the new AMD 7970 reviews that my Nvidia came back to get me.