Please try starting Knoppix with the cheatcode

boot: knoppix vga=0 debug -b 3
from "Cannot boot"
Each time you can see "sh: can't access tty; job control turned off" proceed with [Control D]. If all went well, you'll get the next of the following messages:

Code:
Past mounting /mnt-system
Past mounting /KNOPPIX
Past mounting /KNOPPIX-DATA
Past mounting /UNIONFS
Past symlinks to /UNIONFS
BusyBox ... built-in shell (ash)
Final DEBUG Shell before starting init
INIT: version ... booting
Give root password for maintenance
(or type Control-D to continue)
Now you will see a long list of INIT process
(Scroll up and down the output list of INIT with [Shift-PageUp] and [Shift PageDown])

When you get the message:
INIT: Entering runlevel: 3
root@Microknoppix:/#
type: init 5
and the boot process will start the graphical desktop.