Reply to S4 help!!!

Hey guys,
I have a question for other Traktor Kontrol S4 users!!

I have had this issue where I am mixing, at home(though this has happened during some big gigs too which has made it a serious problem) and my sound blows out.

When i am mixing, and playing with my FX, fx 1 is a gater/beatmash/flanger, and at least one is turned on, then i mess around with FX 2 (an LFO 42 or something), sometimes as soon as i hit fx 2 and turn it on, i hear a big pop, there is no more audio, my master output shows that it has peaked with a red line on it,
and i need to close and restart tractor to get everything back to normal.

you can probably see why this is a problem when I'm playing out, and when I'm feeling in the zone messing with stuff, all of a sudden something gets overwhelmed and i need to restart the program. Its a new macbook, i believe that should be up to scratch.

I can't be the only one this has happened to... anyone have any solutions??
Thanks so much!