Not having experienced this issue myself, it's difficult to determine it's root cause. One other thing I did forget to add before. Some drives have a preference for media. One of my laptops has a QSI drive and simply will not boot from DVD-R media. Burn it to a DVD+R disc and all is well. Don't remember the errors I encountered, but don't recall the one you listed.

The only real cause I can think of is a media issue or a drive/drive controller issue. Try to enable dma using the "knoppix dma" cheatcode as I suggested before. Might want to try "knoppix nodma" just in case it has been enabled and is giving errors as the ones you describe. There is a mention in the Wiki about this concern if you care to look through the "Documentation" links at the top of the page. See this: http://www.knoppix.net/wiki/Using_FA..._to_a_shell.3F