Navigational (global Positioning System) Gps problems of the 2005 GMC Yukon

I was driving on the 55 freeway, and all of a sudden my electrical gps, radio, and power turned off for approx. 5 sec. And the dash rebooted, and radio remained off, and the car was still crusing, but losing speed. I put the car in neutral and had to restart while cruising. It is not the first time this has happened. Spoke to GMC parts dept. On the phone, and he stated there is no recall for this vehicle. This has happened approx. 5 times. I shared that information to the parts dept. And he stated that they could do a diagnostic that would cost a pretty hi amount to check, and if nothing come out of it I asked. Then he stated nothing.