Before you dig in, did you try unplugging the main phatbox cable and plugging it back in again? Both of my phatboxes lose connection to the stereo randomly, and that always fixes it. It's fairly rare, but one day I'll get in the car and turn the key and it will either change the source category to CD Changer and not play, or there will be no source available at all, and it'll just cycle from CD to Tuner to USB. Not sure why but I've had this problem since 2004 so I just live with it. Happens maybe twice a year.