As you can see from http://www.linuxmint.com/forum/viewtopic.php?t=2243
nvidia settings should not be used to change you settings if you have anything but a standard xorg.conf
A simple GUI tool to change the settings (regardless fo your video card) is clearly recommended
I'll see if I can come up with something but my spare time is limited...
I think I could write a script in visual basic that does it, so I have to learn scripting for Linux......
and some glade too