Booting Knoppix 5.1.1 live cd., gives message "Can't find Knoppix filesystems config, sorry." "Dropping you to a very limited shell."
Which takes me to a Knoppix prompt "Knoppix # _ "
What am I supposed to enter?
How can I make live Knoppix work?

When used as a liveCD, you may save any and all preferences you set on applications you use by writing them to a file on floppy/cd/harddrive. The file must be in place the next time you boot the liveCD in order to be able to use them.

Apparently, Knoppix is looking for such a file, and, not finding it, is telling you so, and waiting for a response from you.

If you have access to the web, google up a copy of the Knoppix cheatsheet, which will tell you what you may enter at the boot prompt to get the liveCD to boot to a running session of Knoppix.

My prefered Knoppix boot prompt may be of help to you. Just type this in at the prompt:
knoppix lang=us keyboard=us xkeyboard=us wheelmouse desktop=kde screen=1280x1084 dma splash

Of course, if your language and keyboard are not US English, or your prefered desktop is not KDE, make the appropriate substitution.

Have you used this liveCD before successfully?

I got this exact message when I downloaded the iso image, burned a CD from it, but had not used a product like bittorrent.