twitch/serato dj issue

ok, here goes:

Ive been waiting eagerly for the upgrade to serato DJ since i got my twitch, however i had a serious issue on friday evening at a gig.

after about an hour, i started experiencing dropouts, so did the sensible thing and increased the latency.

However, about ten minutes later, a huge burst of white noise came through the system and the twitch lost all power, i managed to switch to an ipod that i had brought for such an emergency.

I restarted the computer and still nothing by means of output, luckily i still have an old version of traktor installed and always carry my audio 2 for backup, so switched to that and tried it, i managed to get midi signal but no sound so i had to run the evening on the audio 2, had no internet connection so couldnt download a tsi and had to map whilst i was playing.

took it into a repair shop today and they said that they couldnt find anything wrong with it! ran it for about 2 hours today each on both itch and dj and the problem wouldnt come back!

anyone have any ideas?

please though can no-one suggest switching to tractor, as i normally use ssl with cdjs and only use the itch for gigs that dont have any of their own gear , all my crates and history are in serato and its just easier for me that way.

thanks in advance x

EDIT: computer used, late 2008 15" mbp