DJM 350 PROBLEM

Hi guys, as mentioned a few months ago my buddy got a dj package consisting of '2x CDJ 350 & DJM350'.
everything has been working fine untill today, while have a mess about on the decks using VDJ the music just cut completely.

On the DJM the channel volume LEDS just stop showing as if there is no music playing (which there isn't) but on the VDJ the songs are actually still playing, he had his latency set at 'auto' and has worked fine for about 2 months untill tonight.
The only way to get the sound back is to change the latency settings in VDJ config to something else but even then the sound cuts again after about 4 minutes ;/

Does anybody have any idea what the hell is going on?
Laptop specs; windows 7,Intel Pentium,500Gb,x64 bit,4gb ram.
Could it be his laptop doing this or is this indeed the mixer?

Anymore info just ask me!