Cold Weather causing strange happennings to P38 Electrics

Really odd this one - on cold starts - my Sat Nav will not show anything on screen (even though power is going through to it) and although the stereo plays the volume control on the stereo or the control on the steering wheel will not work. Once the weather has warmed up it goes back to normal on restart!!! Anyone got any ideas?

Martyn D

Seems to be a par for the course with a P38, seeing the electrics were designed by this chap