radio doesnt always come on (sort of)

[hamlex]

hi guys,
had this problem for ages now but its no biggy really, just irritating. and i was wondering if its a fairly common thing or not.

at least once or twice a day when i start the engine and the radio comes on, there is no sound coming out the speakers. if there is a cd in, the timer will count as if its playing but no sound whatsoever. The only way to make it work is to switch the ignition off and start the engine again. the only thing i have noticed is when the sound doesnt work i normally get a NO RDS message in radio mode.
its probably something fairly simple i should imagine i'd just like an insight before i take anything apart. once its on and working theres no problems at all.

thanks

Alex

[FarmerPug]

the radio is easilly taken out, check the wires at the back