I have applied all the latest Drupal and module updates, and the audio files are all "playable" again (Larson's conference lectures, and a few other things). Click on ISUS on the top right to get the audio options. Quite a bit of work... I had to reprocess ALL the audio files to be compatible with Flash player, which is picky and won't play a file unless the audio rate is 11025, 22050 or 44100 b/s! But, they are all working again now.