You have told us about your video controler (one I had not heard of so I'm not clear on how well it is supported by Knoppix, hopefully someone else knows). It very likely may help to give us the make and model of your video monitor. And, if you know the specs, what frequency ranges it supports and what resolutions it supports at those frequencies. It could well be that the video system is trying to operate at frequency ranges beyond what your monitor will support. See the cheat codes for parameters that you can use to try to establish a resolution and frequency range that will work with both your monitor and video card.