I just tried to send a post to a thread with only three or four posts on it. As soon as I hit POST REPLY, I got a message saying I didn't have privileges to access that page. This was just after successfully posting to another thread. Since I am obviously able to post this one (so far) I'm assuming there was something going on with that thread. The thread was a little controversial and I suspect a moderator was in the process of pulling it or some such thing. Does this sound likely or is there something else that may be happening here?