Can someone please guide me on an issue I am having with my WD My Passport external drive and my Mac? I have been scanning files and copying them to the external drive on my Mac. I just noticed that once I move a file into any folder on the external drive, it disappears. It showed prior to moving. I took the drive out to a PC and the files in the folders showed. However if I try and copy it, I get the message that the file is dirty. Please help. This is my only copy of the files.