A couple of weeks ago I had kind of the same problem. My desktop was a little too bright to handle normal interaction with the user. So I tried to update my driver for Nvidia Gefore 7950GT. This was NOT easy. A kind supporter from this site guided me on how to install jockey-kde and fix the problem...well, it still wasn't easy as I had to do a clean install of Linux Mint and as the first thing after a fresh install I did an install of jockey-kde. THis fixed it.
But now the problem is kind of back. The screen is too bright now and I even tried all the different drivers in jockey-kde. I even modified the nvidia-settings so that I'm able to set each of the properties of the RBG. This new pane in the GUI is accessible after restarts. But the the custom settings has disappeared after a reboot.
As part of the troubleshooting I tried to delete and/or create a CONF-file which a lot of sites told me that it was importaint to have a fresh version of.
But again: the display is not acceptable!
My question is: is the best solution to do a backup of the system, format it, reinstall Linux Mint and restore settings? That'll take 10 hours and I'm not sure that I'm able to restore all my custom settings.
My second question is: can I somehow expect this procedure to repeat itself every 1 month?
Thanks in advance!