no, pc. its an option. Strangely enough, last night i got it to work by formatting it regular FAT, set to 16 kb. It seemed to me that (the board/forum) says to format FAT32, and that's where the option for 'allocationunitsize' comes up. Can u tell me what the "official" format is. I've done many but the regular FAT w/16kb seems to work so far. Using Vista (if it makes any difference).