Dropping you to a (very limited) shell...
Additional builtin commands available: cat, mount, umount, insmod, rmmod, lsmod.
This is what I see on the screen. I have two questions:

1. minux clearly sees the boot device, since it has gotten this far. Why then can't it see KNOPPIX? I have seen this message before from a CD. I reburned the CD, and the message went away. Now, I've bought Knoppix Hacks 2nd edition, and I've installed Knoppix on a USB using Hack #120. The BIOS finds it, and boots from it. It then reports "Scanning for USB/?Firewire devices ... Done." so it appears to find the USB. Nevertheless, it doesn't find the KNOPPIX file system. How can I get it to find the filesystem? It is now on read-write media, so I can edit files, as necessary.

2. What can I do in this "(very limited) shell"? I have found that ls and mkdir are not available; therefore, I cannot even determine what file structure is present, and I cannot create a mount point. I know the correct device (from a running live CD) is /dev/sdc1. Where can I mount it, and what command can I execute to continue the bootup after mounting it?

Thanks!

P.S. A search on "shell" does not bring up anything relevant, and I haven't seen anything in the FAQs, the KNOPPIX Pocket Reference, or KNOPPIX Hacks that mentions what to do when this error message is displayed.