Inside your iPod nano, or any other device with a computer chip is a radio transmitter. Inside the cockpit are many radio receivers, some of which are pretty critical to the proper flight of the airplane. Your radio transmitter, and radio transmitters being run by other passengers, mix and mingle their signals, producing an unpredictable effect on these key cockpit receivers.
The probability that this happens is not zero or low, but very high.
The probability that this happens is not zero or low, but very high.