I have heard of people having this problem before. I reinstalled Doom 3 after a major system upgrade. The problem is it seems to never save any changes I make to any of the graphic options.
After trying to change the resolution and turning on AA I restart the game. The game will revert back to a low res setting and wont allow me to use any AA. I have changed one setting then restarting the game a few times. Some times I can get the change to stick. But when ever I try to change some thing else it wont save the new change and reverts back lower res.
Should I go ahead and edit the doomcnfig.cfg in notepad then save it as a .cfg file?