ok first thing update your firmware, there is new firmware that allows you to switch from control mode to cd mode and back without traktor freezing, it will however not allow you to switch to USB tho, it will still freeze on you because it is loosing a soundcard, as for the sound dropping out it has to be the lattency buffer size i had the same problem when i first set mine up, i got so frustrated because i couldnt work out what the problem was, i phoned pioneer uk support and they explained how to increase the buffer size and since hten i have never had an issue