I have a external hardrive plugged in. when i delete files from it, it sends it to my macs trash can. When i try to empty my trash can it keeps saying all the files names and says "This operation can not be complete because ________ is being used" and all the files remain in my trash can. But when I unplug they hard rive they are they are gone. When i plug it bak in.. the files r back in my trash can