To be a little more specific (not trying to undercut you or anything, Flynn), at the top of the posts, to the left of where it says, "By *insert username here*", there are little tiny pages, and when the said post is new, the page will be orange. Otherwise, it's white. An orange page will show up next to the title of the thread in the forum as well if there are unread posts in that thread.
It's still acting funny for me, but if it went away for Flynn, maybe it is just my computer...
"Yippie-ki-yay, my friend."
-John McLane, Die Hard With a Vengeance- The TV Edit