During the recent period of cold weather and with the sun showing itself during my drive to and from work, I have found a problem with my dealer fit Kenwood stereo. The controls on the steering wheel refuse to work if it is really cold or if I have direct sunlight on the head unit. Is this just me or does anyone else get this problem. I'd be grateful if anyone knows how to fix this as I have returned it to the dealer 3 or 4 times and of course they can find nothing wrong. Car is an 04 MY ZT CDTi with 23k.