The first bug found with Leopard is possibly losing data if you “move” files rather than “copy” them over to Leopard. Well, 
this is not really a bug as much as it is a possibility of losing files. It has been found that if you are moving 
files from your current Mac or PC, you have a possibility of losing all or some of your files on the transfer. Leopard doesn’t verify that files are fully copied over when performing a “move” transfer. Windows, in contrast, verifies that the files is intact and transferred over 100% when performing a move so this process is safer. However, Leopard only verifies the initial header or first instance of the files when performing a “move.” This could and already has left room for error for some users.
Data loss is possible when moving files rather than copying from a PC or Mac to Leopard because Leopard doesn’t wait for the files to fully finish transferring before it verifies and makes a copy of it. Thus, you should perform a “copy,” not “move” when transferring your files to Leopard. It is good practice anyway to perform a “copy” as this is safer because if your transfer doesn’t work, you can perform it again since the source files are still available. With a “move,” your source files are moved and if disaster strikes, you have no going back.