[IkeRay]

i had this problem in my other car, what was happening was there was corrosion (invisible to the naked eye) on the negative terminal. pulled both cables off and gave the terminals a good scrubbing with a terminal cleaner and the anti-corrosion spray, and havent had a problem since.

it could also be the fuse on the back of the radio, which would require you to pull the radio out and check that fuse.