DDJ-1000 Sudden No Audio in headphones when cueing

Hi.  Every now and then when I'm using my DDJ 1000.  The audio to the headphones cuts out when cueing a track.  the mastercue and channel cue are both active.  It will be working and then just nothing.  turning the headphone control knobs does nothing.  the only way I can get it working again is to unplug the headphone and plug them back in again.

DDJ1000 is selected as the audio device and There's no problem with the headphones when using them with other devices... Any ideas?  

Thanks.  

Matt