Oh, another thing to note is that sometimes, due to some random glitch or something, there is a remnant listing that erroneously tells you someone is in the chatroom (although they have actually left hours before you entered). Before entering the chatroom, I check in the forums to see if it says anyone is in there. If it says there is not, and upon signing in, someone IS in there (or if the number the forums stated don't equal the list in the chatroom), I refresh the page and then the person disappears.
Is this possibly what is happening to you some of the time, Carol? I would try refreshing to see if the person remains in the list or if they disappear. If they disappear, they weren't actually in there when you came in. If they remain, then they're just slacking