Thanks a lot for your suggestions, fingers99.
"-make sure that "non Plug and Play OS" is selected." Yes, that has been my BIOS setting throughout
The "fiddling" with BIOS which I did was enabling a previously disabled serial port.
I'm guessing that I've somehow disabled my PS2 keyboard in XF86, and I don't know yet how to check or reset it.
Thanks again,
chada