Hey,
I too uses Podcasts apps on my iPhone 4S. It does not shows any error to me while i am performing any activity.
U must properly explain your error for download here so i can probably help u out.
I have several subscriptions set up and most work ok, downloading new episodes. Except any CNET ones. I can watch them but get error for downloads. Same on iPhone and iPad, for US and UK podcasts.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic