Almost always this problem occurs because of bad drivers
. "Bad Drivers" means that the correct driver
is corrupted, installed wrong, or has a conflict with a previous or existing driver.
Most times you can correct the problem by uninstalling and reinstalling the correct drivers.
First, go to the nVidia website and download the most current known good driver. (196.21 or the new 197.13 beta).
Then go to Start > Control Panel > Programs > Uninstall a program. Uninstall all the nVidia Apps (3D, PhysX) first, then uninstall the driver (the Control Panel will go with the driver). You will be asked to restart > restart.
When the puter reboots to the desktop Windows will install it's own generic WDDM1.1 driver and you will be asked to restart again. You must do so in order to install the nVidia Drivers > Restart.
Once back on the desktop:
1. You should now be able to change screen resolution. If you can't you may have a defective video card. Windows 7 uses video very differently than XP, so a defect that did not manifest itself in XP will come up in Windows 7.
2. If you can change the resolution then all is well and you can now install the nVidia drivers from your download.
If you continue to have problems you can then try and use DriverSweeper to remove all traces of any nVidia software from Safe Mode. Look up FROSTMOURNE's tutorial on installing drivers to get instructions on using DriverSweeper: Installing and updating drivers in 7
Hope that Helps.