Chosen Solution
I was working in light room and my lacie external hard drive stopped showing up on my desk top. I tried a different usb cable and can feel the external hard drive working but it still will not show up. Before it stopped it said please unplug the device that is using too much energy (best memory of the message) and felt loose like it would say that I did not properly eject the device even though it was still plugged in.
Some of the Mac laptops have different power outputs to the USB ports. Usually the port closest to the power port will put out more power. You can also get this message when an external drive is starting to fail and begins pulling more power. Also, from the desktop, go under Finder (just to the left of the Apple in the upper left hand corner), to Preferences and make sure to box for external disks is checked.
