I'm not sure if that will do anything. It's affecting multiple browsers, even ones that never visited this site before. If it is indeed the same problem the other message board was having, it's a problem with how the board software is handling sessions. I hit refresh there and was given a new Session ID, so that's a possible cause. I'll try and pay closer attention to the circumstances that lead up to the error.
Edit: I managed to duplicate it right now. This is indeed the case. While the sesc was being passed through the URL, I hit refresh, and it gave me a new one, which screwed with things. In fact, I was able to cause it to screw up twice in a row (a first) by subsequently trying to edit this post after hitting back.