You want to have a backup of your waypoints as a general rule, even if not upgrading the software. Yes, a memory stick that someone has formatted in Apple or NTSF format would be a problem. Normally you don't format them, but if formated we would normally do so in FAT file format. (FAT/FAT16/FAT32) You might try diffrent media. Do you have more than one unit? The waypoint database is synced between all units on the bus. If you have a bad USB cable you could always try backing them off of the other unit.