traktor pro 2.5 + CDJ900 + macbookpro 2010 audio problem

I'm having problem with the audio of one (one or two maybe, not sure) of the cdj900 in the club im working at, actually they have 4 cdj900's. Im using HID, all CDJ's are updated to 4.11, i'm using a BELKIN 4 port powered usb hub (with mini usb which i dont like) to connect the two cdj's, sometimes when not so many people i dont connect the power for the usb hub (just for testing it, seems no problem) and the other usb port on my mac is connected to KORG nano pad for FX. My problem is the audio of one of the cdjs suddenly stops but traktor is still playing, the audio wave is still moving and then the audio just come back after few seconds, but last night is weird, audio stops then on again but the audio channel has change side, the left (A) channel on traktor went to the right cdj900 (wtf), i get panic when the audio is gone it was around 6 seconds and then came back on  the wrong channel, this problem also happen once every two weeks i guess but no channel change! i just play some music from a USB flash card then restart traktor wiggle the wires checking it then back to normal work. Is it my usb wires, the usb hub with power or without or traktor? is it the cdj900's? we have 1 cdj900 that have a problem with the play button (other dj's push the play too hard), i already put a sticker (marker) with that player so i will know that one have a problem, but also happens on the other cdj's!!! is it the player's PLAY or Cue buttons, what will happen with the cdj's when get overused? i just heard have audio bug with traktor 2.5, do i need to downgrade my traktor? or my wires need change? help please.

Thanks in advance.