It can appear that sometimes you remove a feed and all the files for a podcast, you sync the server and all is reported fine only to find on a mac in Safari that it still lists some of the information. You might click on a feed and find a link to a file then get an error.
This is not a Podcast Producer fault but in fact a Syndication servers fault on your mac. To fix it goto ~/Library/PubSub and clear it out.
Restart the mac and every thing is fine. It’s all down to the fact the the Podcast Producers page is infact an RSS feed you mac caches it.