Vibrating Video Screen in Game

I have a PIII 550MGZ with GeForce 2MX400 Card. I am running WinXP Pro with 384MG of ram. When I run Gore or Medal of Honor, the screen vibrates causing the same screen to be overlapped twice. I can not make any adjustment to the screen to cause it to stop. I have downloaded the latest drivers from Nvidia & tried the maker of the card Visiontec, but to no avail. I am running the latest microsoft dx also. Any ideas?