i had this same issue with traktor a while ago (mainly when i had the S4). Either upgrade to the new version, or downgrade to a version you didn't have issues with. since i've had the mc6000, it happens every now and then if i'm doing a lot of other things in the back ground, but hardley ever, and never if i only have traktor running. Sometimes the updraged version has bugs in it though, so just revert back to an old version and see if that helps.