I deleted a couple messages from a spammer, and that caused the forum-view page to break, because the message_id's were cached, so the cached result referred to a message that didn't exist any more.
I fixed it by flushing the paginator cache in www/moderate/message-delete. While I was at it, I also added a context bar to that page.
And finally, I also added a cache flush to the message-post page, since people have been complaining that their newly posted messages don't show up right away. They do now.
Hope my fix is okay with everybody.