I just installed the 4.0 last night, today, I was looking through things, and I may have inadvertantly reset a permission.
My site is http://www.copykatchat.com/forum.php , I can no longer see the threads in the CopyKat Chat forum. I was able to do that eariler this morning, now I can't. I have checked the permissions on the forum in the backend, I reset them the default setting, and you still can't get into that forum.