349460 Wordpress/podcast post bug

I have a WP blog with podcast posts (MP3 enclosure triggers audio player to appear). The first 7 episodes have been posted without problems the last few months, very simple and straightforward. I have a problem with episode 8. I save the post with the MP3 enclosure. The audio player appears within the post on the home page. But within 2-3 minutes, the enclosure gets dropped from the post and therefore the audio player disappears from the home page on refresh. On admin, when I open the post to edit it, the custom enclosure field for the MP3 file has disappeared. I have repeated the post 20x but I can't figure out the problem. The MP3 has been correctly FTPed to the correct location. All previous 7 episodes are working fine. This process always works perfectly but something is wrong this time. I need somebody to identify and fix this bug. Should be quick and easy for a Wordpress guru.