Not surprising. The Mac may be trying to boot from the EHD and since it's not a bootable device, it's failing miserably.1) when i boot up my imac and the hd is connected to it won't boot up. I haved to disconnect the hd.
USB ports can be flaky if the connection isn't proper. I've seen USB connections on my Mac go because of a slight bump to the cable. When I say slight, I truly mean slight (depending on how the cable is hit). Is there anything that could be doing this?2) after bootinig up the imac and plug via usb my hd it sees it but after 3 min a message comes up stating that the hd was improperly ejected.
Did you happen to install WD software?3) my imac does not let me boot down when hd is connected.