Unsupported monitor mode?

Hi,

I have just burned the latest version of knoppix on CD. When I boot all looks ok until it starts X and then the monitor displays an error message "invalid input". I assume that this is because it is using some mode my monitor does not support.

I have checked the checksum of the ISO image.

I have tried the following "cheat codes":
knoppix screen=1280x1024 vsync=60
knoppix xmodule=vesa
knoppix fb1024x768

all with the same result (i.e error message).

During the boot it looks like it detects the graphics card OK (7600GT).

I booted into text mode only and looked at /etc/X11/xorg.conf and this looks like it detects the monitor ok, but there's nothing about the graphics card in there.

(PC: P965 E6420 2G RAM, 7600GT, DVD Combo drive)

Please advise.

BTW using "vga=0" makes it work.