Keep having this problem. I have 9 external drives that I alternately use. Three are FW 800, 6 are FW 400/USB combo drives. They are chained to one another from the 800 FW rear port. As my cinema display takes up the 400 rear port I am limited in my options. (The front FW port may or may not be balky as I just resolved a DV camera issue by isolating the culprit as the front port) So when I have two 800 FW drives and 1 400 connected , everything is sweet. When I turn on a particular FW 400 it immediately kicks off ONE 800 drive. I turn it off and sometimes the 800 comes back on line. Sometimes it won't power back up.
I read that the FW drives should be jumpered as master. Is that correct? I have a FW USB hub but i doesn't seem to be connecting. completely stumped