I know I am probably 2 years too late but here's the solution that I found and you won't believe it. Answer: Check the wiring to the rear speakers. If the exposed wiring of the speaker is grounding out, the radio stops playing. I have had this problem for the last 9 months with my 2006 Altima and just found a solution last week on someone else's post. I must have smashed something against my speaker that twisted the wiring connector so that it was touching exposed wire to bare metal. I wrapped the wire in electrical tape so it wouldn't short out anymore and the radios has been working fine. Additionally I was having a problem with my gas gauge not correctly showing how much gas was left. Since I fixed the radio issue, my gas gauge is working correctly. Hope that this helps someone.
