DJM900 nexus2 Weird overal sound after a while

Hi, we have being experienced some weird overall noise (like a filter going true the main sound) on the DJM 900 nexus 2. We are running 4 cdj2000 nexus2 true digital input. and for some reason sometimes we get a weird sound outputting with a fx style.

Its not all the time but sometimes. The last time it happen which was yesterday I had to move the wire (digital) from the cdj to another input and the noise stopped. I tried later on in the same input that had the noise before and no noise anymore. I know its not the wired because its brand new.

Is this something anybody has having issue? or is it a known issue? anybody out there?