My 3 TB ‘My Book Essential’ has started doing the same thing too - right in the middle of uploading photos to flickr. I use it with a MacBook Pro. Initially when I bought it it had problems unmounting at random intervals (after 5 mins or 10 mins etc), but after taking off the WD ‘SmartWare’ that came on the drive I had no further problems. Just last week it started unmounting immediately - just seconds after mounting. It shows up (files and all), loads, and then immediately disappears and gives me a warning about unplugging devices without ejecting. It is still connected however, the light is still on and sounds like the disks are still spinning even.
Aside from hoping that i don’t have to replace a HD that I JUST upgraded, I am really hoping that at least I can recover all of my files, though haven’t had luck on a Mac or Windows based machine so far.
