is it like a chunk of the screen is missing? or is that the entire screen is moved over? this could be your monitor. when i play at 1152x864 @ 60hz, my entire screen gets moved over about an inch. when i force refresh rate up to 75hz, everything is back to center.
i'm using a CRT monitor. it's a weird thing and it happens with this monitor only, no matter what computer/videocard i use. i guess it's just the monitor going nuts or something. by no means do i have a crappy monitor, it's an NEC FE771SB, a great monitor...just when i set it to certain refresh rates/resolutions it moves over.