Cross

Hi. I've got a little problem with my MixVibes Cross. Actually I bought all new stuff to start with mixvibes, new laptop, U-Mix Control Pro controler, DJ set just all. The problem is: when I am playing a track on player one and I am trying to load one on the second player, the sound is breaking and Cross seems to be frozen. Any ideas how can I fix that? What is wrong there? Thx for help.