I've noticed several times a couple of odd occurrences on the forums recently.
1) Sometimes I simply cannot mark a forum as read. I'll read all of the forums, explicitly mark the forum as read, and mark all forums as read, yet the forum will still show as having unread posts. I'll have to leave it and try again later.
2) Sometimes I see posts out of order. This tends to happen when two posts are close to each other in post time but not so close that I could excuse it as simultaneous. For example, I'll ask a question and the question is answered 20 seconds later, but the answer is shown first on my view. I've even seen my post marked as, say 5 minutes ago and the previous post marked as 6 minutes ago. The time is correct, but the view order is mucked up.