I do understand your frustration. There are some underlying technology changes that had to be put in place to allow certain additional features to be enabled. One of these is called "Thread Marking" and is causing the direct impact on the "New Posts" functionality.
There is a strong debate going on in the software vendors website regarding how this search functionality should work with no clear decision. The argument can go both ways on whether the new way of marking threads should continue to display the thread after it has been read or not.
Can I ask those of you having trouble to try and use the following URL:
http://forums.deeperblue.net/search....ew&oldmethod=1
Let me know if that solves the issue for you. If it does i'm going to create a new menu item called "Today's Posts" in additon to the "New Posts" functionality. However I will only do this if enough people request the functionality.