There doesn't seem to be a forum for forum difficulties and this appears to be the best place.
The "View First Unread" feature seems to mark threads or posts as read even when I haven't read them. I have subscribed to a bunch of threads in the Thief 4 forum and I will often go to my User CP to view which ones have updates. Sometimes I'll open my User CP, see a whole bunch of threads with new content (and the down arrow to jump to new posts) and I'll read a couple of them and go away for a while. When I come back, I am often finding that a lot of those threads (but not all of them) that had posts I hadn't read are no longer showing as as having unread posts and the "View First Unread" button doesn't appear when I visit them. I have been unable to discern a pattern so far.
I know for sure there is a bug since I made a post in http://forums.eidosgames.com/showthread.php?t=88598 a couple of days ago and definitely hadn't read it since, but when I went to my subscription list, I could see there was a new post but it wasn't marked unread. I went to the thread and again it didn't have the unread button on it.
This is making it hard to keep track of the threads I'm interested in and when they get new posts.
Running: FF 3.0.10 on Windows XP