I installed a backup program recommended by PcWorld on my new laptop because Acronis is no longer included on a WD backup drive - "Perfect Backup," and it wrote a very deep recursion of the same several folders until my brand new 1TB drive was full. There were 3 folders each 3000 folders deep. I know how deep it was because after about a half an hour of trying to delete them, I found this page, and the robocopy solution saved me from xkcd-ing my laptop off my desk.