my hitachi external drive 3 tb disappears from My Computer every time I shut down the pc(windows 7).To reconnect, I have to unplug its power supply and then plug it back in.Can anybody help?
Couple of things you might try.
1) Safely remove Hardware before shutdown (System tray).
2) USB Root Hub - Properties Power Management
Uncheck the turn off power box. ( All Hubs)
(I read that Win7 & some drive mfg's conflict with power mgmt for USB.)