Screen problem, GTX570

Hello, I bought a computer a couple of months ago, it has the graphic card NVIDIA GTX 570. I have not been having problems with the graphics earlier, but i had problems with blue screens so I sent it back to the company I bought it from and they found out that the motherboard was causing it so they switched to a new one. Got it back today and I have installed the latest graphics drivers from the nvidia site.

The problem is, the resolution is wrong and the display is dizzy. So I rightclick the desktop and navigated to the screen-settings and it looked like similar like this:

Screen: "Not PnP-display Screen"

And max resolution should be 1920xSOMETHING for a 24'' but its like 1690xSOMETHING. I am using VGA from the screen to a DVI-contact and then into the output DVI in the computer. I have tried in both DVI's. Maybe I need some drivers for the screen, I cant find them and I have tried. I dont have the CD because I bought it cheap from a friend. Its a BENQ E2400 HD(it has HDMI).

Thanks alot, I cant wait to start playing...