Leopard bug in moving data reported
Tom Karpik, a computer science student at the British Columbia Institute of Technology, says he has identified a bug in Leopard that can cause you to lose data if problems occur while moving files between two different storage volumes, such as two different hard drives. Apparently, the problem is that if the source of the file crashes or is disconnected from the network while the move is under way, the contents of the file completely disappear from the source machine, and you're only left with whatever had already been copied to the destination machine.
Commenters on Karpik's blog, Slashdot, and others like Daring Fireball's John Gruber point out that you're asking for trouble if you opt to "move" files rather than copy them, notes CNET. An easy way to avoid any problems is to just drag the file from one volume to another without pressing any keys, and if you really want the file gone from the source machine, manually delete it after everything has been completed.