I have this problem too, but find it most when I have somehow been (or accidentally) logged out and had to log back in ~ I sometimes accidentally log out of WM therefore logging me out of everything... or when I have had to reboot my computer or something like that. Yesterday I was reading the New Posts list and it all of a sudden said "No New Posts to Display" or something to that effect and I would only get new posts as they came up, no matter what specific topic, although I could go into specific topics and it would list all the threads under that catagory... as they would build, the list would get longer again, until it was the entire day... I never know when it will happen... I also notice that when I use my work computer to read posts there, and look at the same forum on my home laptop, that they show differently (unread when I had read them at work)...
I do think that this forum is better than some I have seen in the past...
SNM had confirmed yesterday that there were issues with my WM that they found and are working to fix them, so I feel better about that.... and assured that there were more updates forthcoming!