Ahhh okay.
I thought maybe the contents of the file was moving during the transfer. As an example, if it "moved" 50MB out of 75MB and lost power, I'd have 25MB on the source and 50MB on the destination leaving me with two partial files that are now corrupt.
Usually I select 'copy' when doing something like this, however, it's so rare power is lost that I will "move" files instead. The power outage last night was probably the first time in a few years; and lasted about ten-seconds.