Are you using the official driver from nVidia? There seems to be a difference between "nv" and the official "nvidia" driver. On my system, the official "nvidia" driver works great, while the default "nv" driver tends to shift the display to the right about half an inch.
i also have this problem,my display card is ATI Radeon 7200,may be i have not its drive ,now it is 800*600 when change to 1024*768 . reboot, my computer can't enter the linux. why??and how i to resolve this problem??thanks