Sudden distortion, kind of metallic noise

Hi Guys.
Im just about to do a weekend of gigs with my s4 and traktor pro.
All is upto date.
Ive been using my iPad up until yesterday using Traktor DJ, which i must add is amazing and I've nothing bad to say about it.
SO last night i was pre-preparing a radio show and put a guest mix on for the middle of the 2 hours and wandered off to watch wales and portugal. I went back into the studio to see how long there was left before i had to do my ending set for the show and it sounded a bit like my speakers had blown. So i listened on the headphones and indeed the metallic noise was coming from traktor.
So i abandoned it and left it for today.]
So here i am hoping you guys have you had this happen and can tell me what to do. Ive about 12 hours to have this wrapped up before i head off to sheffield to do gigs.
To me it is reminiscent of when my Apogee Duet sound interface for my studio, loses the plot and the iMac has to be restarted. Its the same horrible sound it makes.
Im guessing that it will be a buffer setting or summat. Please help if you can id be very very grateful
Lee