When booting (i use Morphix, a derivative of Knoppix and it's the same problem), boot zith the following option:

morphix dma

or then for knopix, i think:

knoppix dma

It fixed this problem for me.

Now I have another one, my libnsl.1.so got somehow corrupted and i can't login into my system (on my hd), and when booting knoppix/morphix, it says :
hda: unknown partition table.

Now it's my turn, please help! but