I also have this issue, just as the OP describes. I set my resolution to 1280x960 at 100Hz, but everytime I load the game or if I alt-tab out of it, it changes to 75Hz. The setting does not change in the options, but I notice the flickering and my monitor's OSD shows 75Hz. To fix it I need to change a video setting in the options and when it asks "Do you want to keep these settings" I say no and it reverts to the proper setting. Kind of annoying as I have to do this with each load. I don't have this issue with any other game.
DW
