Using a Mac to copy .imi files to SD card problem

I have tried twice to copy one or more .imi files to an SD card (formatted on a Triton 500) and found that the Triton could no longer read the SD card. The Triton became stuck endlessly with the circular "clock" just spinning. No error messages are given and power key will not shut the unit off. Needed to remove batteries. The Mac was running OS X 10.6.2 (Snow Leopard. Could find any gratuitous files on the SD card that may have been written by the Mac, hence believe that it has corrupted the card format or is writing hidden files. Resolution was to copy the maps from the SD card to a PC (Windows XP), re-format the SD card in the Triton, then re-copy the same map files back to it. The SD card then worked fine. If this is a known issue, sorry to re-post. If not, beware of the OS used to copy map files.