Just in case you think you missed something, here's a tip. When you click on "show unread posts since last visit", and you read the post you missed, don't forget to scroll down under that post. Usually there are more unread post under that one. Like last night, under the Rhea Mae topic, I read the first post then scrolled down and there were 5 more I haven't read. This is why sometimes we find 2 or more of the same discussion but in different areas.
So when your in a topic, keep scrolling down until you read where you left off. You will find many that you missed and probably an answer to your question!
