What drivers are you running. With that card I would recommend the 91.31 WHQL drivers get them here;
http://downloads.guru3d.com/download.php?det=1415
you may want to follow this procedure; from the control panel use the program removal tool to remove the Nvidia Video Drivers, then reboot, ingnore and say no to all prompts. Then use a driver removal tool like Detonator Destroyer or something similar to remove all instances of Nvidia video drivers left behind, Nvidia drivers are notorious about leaving stuff around and if you install over the top of them you are asking for problems.
Reboot, ignore all install requests. Then execute the new drivers and reboot. Reset the resolution in the Nvidia CP.
That is the procedure that needs to be followed when changing Nvidia video drivers.