Re: Integration issues?
I had that same problem, and it just went away on its own (?). One situation in which you will get the Topic Closed message (even when it is open) is if you look for a page that is beyond the actual number of pages in a topic. Sometimes (I don’t know why), after posting it will take you to a page that does not yet exist, thus giving that message.
I got rid of front page topics, and that seemed to fix the problem. But, since you’re not running front page topics, I have no idea why that would happen.