I had the same! normally when you use failsafe in the knoppix prompt it should work, but then it can happen that not all other stuff is recognized!! try knoppix screen=800x600 depth=8! Send me a PM if needed since I do not follow this thread.. if this does not work start in prompt with expert (not knoppix expert) and then when it asks you to re-configure your X11 system, try that!!