I usually place the gamma levels up, because I have a dark screen, but mid way throught the game they revert back to the default settings. Any help would be appreciated

Please tell us some more about your system. What if you set gamma levels in config.cfg?

If you have a screensaver, try if disabling it helps.

it was the screensaver, set it for longer than 10 minutes an it is fine, thanks

If you are using linux/gnome this might be of interest: http://forums.alientrap.local/viewtopic.php?p=41052#41052