My guess was that the security settings were blocking the cookie because of a lack of a compact privacy statement. It would, for a time, maintain what are called "session cookies" that would let me navigate for a time, but if an action "handed me off" to a sub-server before bringing me back to the forum, it lost the session cookie and appeared to go "braindead" until I re-logged on. I'm guessing by essentially putting the forum into my "okeydokey" safe list, it's enabling regular cookies and keeping me logged in.
At least, that's my theory. I could be wrong.
EDIT: That appears to be it. I even hit the "Jump to...GO" button and it kept me logged in this time. Woohoo! Seems we figured that one out. And none too soon, either! I was really worried I'd have to install that satanic commie Firefox software!