A bug in Win7's Media Player: It can play video DVDs that have normal moving picture and sound. But if the picture is a non-moving still photo, the soud comes out with severe dropouts. As soon as the still photo is over and the picture is again a moving one, the sound is ok. An ordinary DVD player connected to a TV played the same DVD without hiccups. Because the DVD was authored at home, the investigations were easy. The DVD was encoded using variable bitrate. Media Player's sound decoding can't handle the situation, where the video bitrate is low due the not changing picture. No matter, was the sound encoded using PCM, MPEG or Dolby Digital. When the video in DVD was encoded using constant 6 Mbit/s bitrate MPEG-2, its sound played continuously also in Win7's Media Player. That was a good lesson to learn before giving out some material that must be generally playable.