In the column showing the number of messages logged for each thread, some of the larger number are shown in blue, underlined, suffixed with the letter 'd' and asterisked. What does all that mean?

Have you tried this?

On the Forum Menu, there is a "messages" column that shows the number of messages in a thread. If there are more than 50 messages in a thread, the "messages" number becomes a blue clickable link. If you click that, the messages will be displayed in groups of 50. Next to that clickable number link is a small letter "d" which is also a link - if you click that, it will display messages in reverse (descending) order in groups of 50.

It's a little-known feature that Jeff designed, and some people have found it very useful.
-Joe Offer-