I think that libc6 could not be replaced properly. I would suggest the following attempt.

Reboot your Knoppix into runlevel 2. You can achieve this by adding the number 2 to the list of cheat codes. Usually
Code:
knoppix 2
is sufficient.

In the shell issue
Code:
chroot /UNIONFS
dpkg -a --configure
apt-get -f install
exit
reboot
This time boot into the desktop environment and try to find out whether there is any issue left.