klaus2008 you're a genius! Your suggestion of putting
"initrd /boot/isolinux/minirt.gz" on a separate line works! The stick now boots.

I've spent such a long time trying to install Knoppix on a USB stick. So I can't
tell you how grateful I am for your help.

Is "initrd" a grub command? And could you tell me WHY putting the "initrd .." on
a separate line works, and why putting "initrd=.." on the "kernel" line doesn't.