I have a Sager 5670
3.06GHz with ht
1GB Ram
ATI Radeon 9000 128MB

I had HyperThreading disabled in my BIOS and I was getting basically the same symptoms described by 5150 users. After reading emanuele's post, I remembered that I had HT disabled, so I enabled it and Knoppix boots easily now.

I don't know what control you have over CPU hyperthreading in your BIOS, but on my comp:
HT disabled = Knoppix won't boot
HT enabled = Knoppix boots

Note: Since I installed Windows XP with HT disabled, if I change this setting in the BIOS I would have to reinstall XP. But I am happy that I know how to get Knoppix working now.

Thanks