All of a sudden the posts that I have read are no longer identified; all posts stay in boldface even after reading.
I have looked in my user CP for anything that would affect this but have not found anything.
I use the same computer all the time and thus the same IP address.
I liked this feature as sometimes I forget which posts I have already read..
Anybody have a clue on this?

 

That has always been the case for me. I believe it means that someone else is viewing and or adding to the thread. If I am the only current viewer/poster, it will un-bold after I have left it and returned to the New Posts page.

 

It means someone else added an additional post. If you click on the New Posts header it will go away after you've viewed it or be moved up in the lineup if someone added to it.