Hey, it might have been a Bad burn, the program you burnt it with may have not written the ISO correctly, or the burn speed could have possibly been high. I have no trouble running 4.0.2. on my Dimension 3000, except I have to type "Knoppix DMA" every time I boot otherwise i get a "KNOPPIX Halted" Error, X11 cannot be started. However, I have a really big problem not being able to install KNOPPIX to my HD, even after the correct partitoning, due to a "Bad Superblock" error. There is only 1024 MBs used to boot, and there is no way I know of resizing the Cylinder Boundaries. So try to burn the ISO using a different program or a slower speed. Hope this Helps.

~Frustrated @ Superblocks~