Yep, Ripster, Floppy is the culprit! As soon as you unplug and replug all is well, but a little inconvenient, at times I guess I'll have to break down and buy a Blue Cube and see if that is any better. The generic GE USB dual adapter wouldn't work, either.
Interestingly enough, plugged in to the Thinkkpad Dock's PS/2 port, a Model M works perfectly without adaption. Those of you with docking stations may not need adapters!
Perhaps IBM (who designed the Thinkpad dock before Lenovo took over) kept things backward compatible on purpose. TPF