I've had the car in the dealers this week for an unrelated problem (engine kept stalling). It turned out to be a bad earth.
Since I've had the car back, on a couple of occasions, the front 2 windows have refused to come down when the switch has been pressed. You can here a very slight movement but then nothing. Both times I was at the multistorey car park barrier and had to pull forward and open the door. The windows then worked OK when I pulled away!
Seems a strange one, but would anyone have an idea whats up?