Reply to Traktor with Windows 8 problem

I recently purchased a new, more powerful laptop for my DJing, and of course it had to come with windows 8 :/
I am running Traktor 2.6.1 , and when I plug in my S4 mixer, i get a lot of audio feedback through my speakers, like a squealing sound. I tested my old laptop, to check it wasn't my mixer that was messing up, but it seems to be the new laptop.

Is this a windows 8 problem? My old windows 7 laptop (Toshiba Satellite) works perfectly.
I tried to call Toshiba Support, but they wanted to charge me to diagnose the problem.

Does anyone have any ideas?

Thanks guys