No, I hadn't seen your parallel thread, oldgeezer. Thanks for pointing it out. The suggestion to try dmesg was particularly helpful. I got the error message "device not accepting address". The FAQ on linux-usb.org suggests that when you get this message, passing the noapic boot prompt to the kernel can solve the problem. Sure enough, when I tried booting with "knoppix noapic", the printer worked.

Thank you both for your advice.

-Rob