Got a 120G Maxtor "internal" hard drive hooked up as AC/firewire
external using a kit. It worked fine at first, then my desktop
(Dell/XP pro) started not recognizing it. I'd have to unplug/replug or
turn it off and back on for it to be recognized. Finally, it won't
recognize it at all, though devices dialog sez it's connected. Then
the same thing started happening with my laptop (Compaq/XP home) and
now neither will recognize it -- the drive's an orphan. Ideas?

Do you have another firewire device that you could test out on the
port? It may be that the drive is bad and damaging your firewire
ports.

If other firewire devices work ok then try to go into the device
manager uninstall the driver for the firewire port and let windows
redetect it and start from stage one and see if that helps.