The big meeting room got double-booked today, so the Wednesday matinee had to be moved upstairs, using the older portable projector and a laptop. But we couldn't get the laptop to play the DVD. Windows Media Player would play the video, but not the audio. IntermediaDVD would not play at all, complaining that the DVD was copy-protected.
So I downloaded and installed The Combined Community Codec Pack, knowing that Media Player Classic is bundled with it. Media Player Classic played the DVD without complaints, and now I have a laptop that can play DVDs, AVI files, and several other media formats that it couldn't play before.