Fix Nvidia card resolution problem in Ubuntu (works in 9.10 too)

Sometimes the nvidia x server fails to recognize all the resolution combinations. This is how you fix it: 

Add Option "ModeValidation" "AllowNon60HzDFPModes, NoVertRefreshCheck, NoEdidMaxPClkCheck, NoHorizSyncCheck"

Under device section in the xorg.conf in /etc/X11/xorg.conf

Source: http://ubuntuforums.org/showthread.php?t=444960