Hmm, well you can always use Knoppix
and when the Knoppix prompt appears enter knoppix 2 ... then mount your root partition and edit /etc/shadow. It will look like this (the first line
So in this case to reset the password (no password set) remove the 2nd part (starts at first :) $1eNq5hBUx$lTkmKii66qdLZwHz4QKBA/ until the 3rd part starts (next :). So it will look like this:
Now root has NO PASSWORD. If you have network connection I advise you to unplug it otherwise you have a real security problem ... after that jsut reboot and login as root and set a new password!