Yes I understand the star thing when you're looking at the forums normally, but I hardly ever do that unless the forums mess up for me which has only happened a couple times for it not showing any new posts yet there were some. It's like it just up and hit the Mark Everything Read for me without me telling it to, so now I have to go through and find all the new ones manually lol. Dunno why that happened to me at all but it did it a couple times only so that's not too bad.
As far as the stars though, I never see that stuff unless it's something someone posted in as I always use the Show New Posts as my main page when I load the forums even, that's what I have bookmarked and what loads right away for me. So it's not the star things that are stuck at the top for me, it's just some random post that just won't let itself be set as read to me. Once I read it all and use the Mark Everything Read link it goes away. The issue with not marking things read though is there 100% of the time for me, no clue why at all. I just clear it out periodically and I pretty much ignore it since I only read the new posts anyways to start with.
Could be a browser issue, a theme issue (which I doubt as I don't theme Firefox all that often, and it happens when themed or not themed, happened with and without Windowblinds turned on at all also, and whether I have Windowblinds set to skin FF or not doesn't matter either.
No clue, just happens to me as everything else does I guess LOL.