I often find that I can't view threads. I click the link into the thread, nothing happens. I copy+paste it into the address bar, nothing happens. I log out and click the link and I can view the thread.
Sometimes it happens sporadically, allowing me to view the thread after a lot of clicking. Other times, I can't view the thread at all. But when I log out, I can see everything I want! This only happens on specific forums, hasn't happened off-topic yet.