DDJ-SB FAULTY AND DELAYS STICKY!

Ive purchased a ddj-sb from djcity melbourne and while i play tracks the audio goes fairly staticy through out most songs you can really notice it at first if you are audience but i certainly do notice it, after maybe half an hour to an hour all the tracks that i load or anything i do is slowed right down and is a glitchy and sounds like shit you cant do anything with the controls to change this, the only way to fix it is to unpulg the controller and plug it back in then it resets to normal bpm and a little bit of static, note to self this happens on a regular bassis and i cant have it be doing this during gigs it will cost me alot of money if its not delt with or replaced!

any idea of what this might be??

i think it might be the cord but not 100% sure

running asus laptop windows 7 32bit

serato dj full version (payed for)

serato ddj-sb

2 ave revo 15 inch pa speakers