The unread issue is usually caused by the user moving to quickly. Basically, when it determines if there's a new post in a thread, it determines it based on if you've 'seen' the new post, or loaded it. If you submit a post and then move, you'll have moved before you loaded your own post. If you have slow internet or wonky service, that makes the problem even worse.
Erin: what system are you working on?
Algae creates 75% of the world's oxygen, so really we're all just doing our parts...