Rekordbox copying the wrong files on USB?!

Hi! I have a big problem! When I'm creating a new playlist on Rekordbox and for exemple, I dropped 3 track in it...when I exported the playlist to my USB, the 3 track was 3 complete different tracks.  I disconnected my USB and reconnected it, then I did the same thing..now the name of the track I copied are good but the actual tracks is the same 3 random tracks of before?! How i can solve this problem? I have a gig in couple days and can't copy new music! 

I readed on forums that's maybe a track ID issues, or something..but how I can solve this, or at least reset something?!

Thx in adance.

Alex.