Do not use the 320.18 drivers. They will cause nothing but problems and they'll be difficult to fix. I've been suffering from the same thing for the past few days. In case you've already installed them I suggest you follow these instructions I found online as they might help:-
You'll need:-
*Compatible/Working geforce driver for you GPU extracted from Nvidia installer to a newly created folder on your desktop.
*Installed Driver Fusion, aka Driver Sweeper Link:
http://www.treexy.com/media/30691/driver_fusion_1.6.0.exe*Installed CCleaner Link:
http://www.piriform.com/ccleaner/download/standardFirst: Boot into Safe Mode follow instructions below!
*Win7 -Restart PC and keep hitting F8 on your keyboard until you see an option to select Safe Mode.
*Win8 -Open Notepad, copy and paste the following command line: C:\Windows\system32>shutdown /r /o /f /t 00
-then save-as this text file with the following name onto your desktop: SafeBoot8.bat
-Now once you run this created batch file your PC will reboot into SafeMode Menu, select option 4 for Safe Mode.
Second: Once in Safe Mode Go to your device manager!
-1- Win7/Win8 hold down Windows Key on your keyboard & simultaneously press R, paste the following command and hit OK: devmgmt.msc
-2- Now expand Display adapters by clicking on the small triangle then right-click on your Nvidia GeForce GPU and select Uninstall.
-3- Then open Driver Fusion Utility and select/mark Nvidia Display & Nvidia PhysX & hit analyze, delete what ever it finds but don’t click on reboot just yet.
-4- Open CCleaner and scan registry several times until it finds nothing once finished reboot your Win7/Win8 PC back into Safe Mode.
-5- Repeat step 3 & step 4 above until Driver Fusion finds nothing, rebooting into Safe Mode each time until finished.
Third: Installing working driver from Safe Mode!
-Open GeForce Driver folder that you had created previously from an extracted driver at the beginning of this guide, and right-click on setup.exe & run as Admin
-Click Agree & Continue & select Custom/Advanced option & deselect everything that you don’t need or have use for like 3D crap but make sure you select clean install.
-Finish Installation and reboot normally