When this happened to my TiBook 500 I ran the diagnostic CD that it came with. Showed the port as bad at which time it was repaired by Apple. > Thank you for your suggestions. (I'm new and jumping in here.) I followed > all your suggestions (my iMac has stopped recognizing firewire devices). I > zapped the PRAM and rebooted for the firmware. When I got to the re-set (The rest of this overly long quoted message has been deleted.)