Problems with Music Files

So my new car has a usb connection to play music from (which is awesome!!). However, when I plug my usb into the car’s usb connection and try to play music, it works, but every other track is “unavailable.” However , there is no “track” there..i.e. if my music folder copied from mac os x 10.5 has 12 songs, the car reads 24 files and file 1 will play song 1, file 2 will be unavailable, file 3 will play song 2 from music folder. My assumption is that Mac OSX is adding in some kind of invisible file or something, but I’m not sure what’s going on, would anyone happen to know?

thank you!