I haven't encountered this problem, but I am having something unusual happen. When I normally access the site, I get the main page, with the 'Annouincements' and the boxes to login in, in the centre, which will show the avatar etc. Now, I get the forum pages, with the small log-in boxes at top right, and the note about 'If this is your first visit....register....'etc.
I the have to complete these, and ensure i click the 'Remember Me' box, otherwise I lose connection after aroiund 15 minutes.
Not a major problem, but irritating and unusual.