I had this same problem the first time I installed the OS on my work PC, using a GT420. I would suggest when you first install Windows 8 you:
1) Right click on "My Computer" and select the "Hardware tab". Select "Device Installing Settings" and choose "Never install driver software from Windows Update".
2) Get Driver Fusion
, but don't run it yet.
3) Go to your "Device Manager" and under "Display adapters" right click on your GPU and select uninstall, tick the box "Delete the driver software for this device" if it shows.
4) Reboot into safe mode
5) Run Driver Fusion and restart.
6) Install the latest Nvidia Driver.
Basically that's how to clean install Nvidia drivers.