At the suggestion of one of our members, I made a small change to the forum settings. A lot of us are busy and don't have time to read all of the new posts in a single session, but when we leave the site for a few hours and come back, the posts we haven't gotten to no longer show up as unread posts/threads.
The change I made will leave the threads unread until you decide to read them. Initially, you'll notice a lot of threads under the new posts page that have not been updated since your last visit but still contain unread posts. Those are just threads that don't have the new flag indicating that you've read them, even if you already have. As you read the various threads, that list should shrink and/or go away. If this feature proves to be useful to everybody, we'll keep it, so if you feel strongly one way or the other, please leave feedback in this thread.