FP937s 1280x1024 doesnt work

[Poldi]

Ok, here is the problem:
Every resolution works fine on my BenQ-screen except for the highest (1280x1024).
When I change the settings to that resolution, the screen becomes black for 10 seconds stating "no signal detected", then my old resolution pops back.
I took the PC from a friend and my screen -> no problem at all.
I took his screen and my PC -> no problem with the resolution.

I wrote an email to the tech-support of BenQ, they said it must be a gfx card issue.
I got Geforce FX 5700, I tried the newest driver (there is one general driver that works on every nvidia card) and the newest detonator driver. Same result.

Any help would be greatly appreciated, I hate the tables overlapping so much while multitabling.