I made the same expierience, couldn't get the installer to work.

I made also
sudo rebuildfstab -r -v
export IGNORE_CHECK=1
sudo knoppix-installer

with the same result as discribed above

I have only 1.7 GB diskspace for root, perhaps this is the problem.
Is there a way to chose less packeges?

Well I rezised to 2.2GB space, then it worked perfekt!