Your NAV unit in the trunk has failed. The stereo goes out when the system tries to initialize the NAV unit, kind of like a reboot. That disrupts all the hardware on the fiber ring which is why your stereo goes off for a moment. You may find that after the NAV unit cools it may work again, but be assured it wil fail permanently soon. Look on eBay for a replacement.
I don't have all the answers, but I can do one helluva Google search!