problem with cd900 nexus

Hey 

i have cdj900 nexus 2.3 & mixer 900 srt 1.13 update

i work with serato dj with new MacBook pro retina ( sierra ) 

my problem:

the song playing and sometimes  at a random moment the song 

go back to the start and continue to play (like hot cue)

i glad to get some help

Regards

Gil