I recently purchased this WD My Book 3TB USB 3.0 external Hard Drive. I took it out of the box and followed the quick start guide which was very simple - Plug it into power, Plug it into your PC, done. It loaded some drivers and recognized the drive as Windows 7 would with any new device.
I then updated my Windows 7 backup schedule to go to this new drive and started the backup process. About halfway through I got the dreaded error: "The request could not be performed because of an I/O device error" Error code 0x8078002A.