My best guess would be something interrupted the download, and the partially downloaded file sitting in the folder is blocking a new download/replacment.
Assuming you are using ITunes, If you would go into you MY MUSIC directory, to podcasts, to escapepod, and delete the offending file, you should be able to download again and it should be fine.
I really do recommend Itunes, it works well, is free, and automatically updates podcasts for you.