Hiya mate,
This has happened to my mates clio. 07 plate.
My two cousins are renault salesman aswell and theyve confirmed what the problem is.
The radio's cant handle the cold temps and they break when they get below a certain temp. I heard it was due to an old trick of breaking the radio code was to put it in the freezer and it would work fine. so renault put a thermostat in the radio to shut it off after it reaches a certain temp (dont quote me on this lol)
But bottom line is that renault know the fault and will replace the stereo free of charge.
Google the problem, theres loads of forums around that state this.