pro dj link

 Hello problem after yousing 4h the Pro dj Link my setup is a Macbook Pro. 2x cdj 2000 nexus & DJM 900 Nexus..and a Lan Hub ..after playing with no problem in the club for 3 h from Recordbox lan with sync buttonn and sometimes without .. recordbox startet when i was loading the tracks in to the player to pitch the tunes down for 2 seconds after that he played them right .. after 4 h in the end of my set in the middle of the tune with sync on recordbox ore the players? starded to pitch (ore pitch) the  latency of the trach down in the middle of the tune i coudnt do nothing i released the sync mode and stopped the tune and played it again after that he played the tune in the right speed  again ..

my question is why he done that ? why recordbox piched the tunes down by himself?

sorry for my english;-)