Try getting new drivers, i would be pissed off to if i had that problem, but you must remember just how fast an x850 is. Though with a 7800 you should be able to run it on full easily. I never use the normal setting in games, i always use the custom ones, so maybe try turning off some effects and putting the other stuff up a bit, however a low rez game with full effects is likely to look better than a hi res game with no effects, so it's your choice. But seriously, update your drivers, use a driver cleaner first.