Weird, I just hooked up my external FW harddisk to my parents' eMac to transfer some files and after several seconds of transfer the harddrive would unmount, requiring it to be powered down and up again (the HD that is). When connected idle, without transfer, the HD stays mounted. There is an iSight connected to the eMac as well, but not in use while the HD is connected. I tried to disconnect the iSight and everything works like a charm. Could it be a lack of power on the FW bus that's causing the unmounting?
Back at my place, connected to my cube, the ext HD works flawless, even while my iSight is connected. Does that mean that there is more power on the cube's FW bus than on the eMac's?

No dangerous problem here, just curious why this happens. Thanks for insights!