I was driving the other day and got caught in a traffic jam. Seeing no possibility of moving for a while I decided to do one of the language lessons on my nano. I really thought it had broken - the screen had rainbow colours on the bottom and when I started it up the screen was dim and the colours didn't go away. My heart sank a bit but it seemed to play well so I listened to it for the hour and ten minutes it took to go two miles. When I got back home I had a look at it and it was fine. What was the problem? Polarising sunglasses!