This is a question mostly for the admin or someone else who has access to the Admin panel.

I have a problem where when I click on the "take me to the first unread post" from my UserCP it does not take me to the first unread post. It always missed a ton of new posts and I have to scroll up to find a post I've already read and then go down from there. It's a total PITA. I also run a vB4.2 forum and don't have this problem on mine. You can PM me if you want to discuss it privately. The following setting is what should cause this. There's 3 options here, mine is set to the first one.

Admin CP -> vBulletin Options -> General Settings -> Thread/Forum Read Marking Type