uhm interesting one

1) have you tried booting the CD on another PC that you know boots OK from the CD

2) have you tried to boot on your laptop with a known good booting CD, ie windows XP or other?

3) with another distro that I had that would not boot I made a boot floppy and booted from that and got the CD running and installed. You can probably do the same with knoppix, but some one more experienced than I am will have to help you, if you cannot work it out for your self.

HTH