My radio dies..

[Hosse]

First post:-)
I´ve allways had this problem with my stereo. It´s a 16:9 navi with 6 CD changer. When I haven´t used my car for a day or so and take it for a ride, the sound on the stereo dies? The sound doesn´t come back untill I ;
1. turn of the power for several minutes or
2. shut down the engine som some time or
3. start to navigate and wait until the nice lady says something.

Isn´t this strange? Anyone else who´s got this problem?

Thanks