Jack, Dan, yes this is exactly the problem I had, I suspect it is a weak internet connection or at any rate some kind of faulty connection.
I ended up trying to make a post and then going into my profile, finding my attachments, trying to make a post to the post and then picking up an error message, I found if I intercepted that message quickly enough (something like "if not redirected click here") I forced the app on a different direction and then eventually it corrected itself. I also went into my posts and attachments and made a reply to myself knowing it would not work, it then sometimes redirected itself and eventually I got the correct skin for BPN. Not terribly helpful I'm afraid.
I also went repeatedly into different forums keeping the tabs open and I think on one occasion it worked.