Thanks for your suggestions. The DVD has been burnt properly (as tested with md5sum and dd) and the onboard sound has been disabled.

The problem is still unsolved.

To those with a working soundcard using the Knoppix DVD copy please run sndconfig and see if it comes up the same soundcore.o missing error. To do that click on the penguin icon (bottom left corner next to the K icon) | Configure | Sound Card Configuration and tell me if you come up with the same error message.

Thanks