The new thread button in the Bug Report forum is now working for me. The spell error highlight (red line) never is consistent no matter the forum. Often I'm deep into composing my post before a mistake is underlined yet previous mistakes are not flagged until I run the spell check. Usually no mistakes are highlighted and I know there are mistakes. I dunno how to tell you to reproduce it except to say misspell lots of words and see what happens.I bet there is a conflict between your spell check and Firefox.
As for getting logged out, yesterday was the first time I got logged out when I was already in the Lounge and I tried to jump to another thread. Usually I'm logged out when I first open the Epic home page and I'm looking at the generic page, not my personal page. I never deleted cookies or unchecked the 'remember me' box. It just happens.
Ha, just now I used spell check and sure 'nuff there were mistakes that were not highlighted. I corrected one and left the other. When one was corrected the other was then highlighted. The only other information I can give you is that when I reply to a topic I usually use the reply button at the bottom of the page, not the one at the end of a previous reply.