Occasionally the multitronic gearbox does not engage for approx 10 seconds on selecting drive or reverse. This seems only to happen when the car is driven from cold for about 5 minutes. The engine does not respond even if the throttle is pressed fully. This is an intermittent problem for the last 2 years and Audi cannot find the problem because it doesn't do it when they have the car. I have asked Audi to record my problem as it started while under warrenty. Any ideas?