Odd: the forum doesn't seem to remember my login from one session to the next. Perhaps the cookie recipe needs adjusting?
Happens to me too when I follow the link to the forum on Minna's site. But everything's fine when the link is chosen from bookmarks or typed manually.
I suspect this is because the link on Minna's site doesn't include the https at the beginning, and login cookies have been set to https-only (for security). I'm considering putting a redirect to https for the site, which would resolve that. In the meantime, try just typing in
https://ssssforum.com in your browser bar and see if it works properly then.
ETA: I've added in that redirect, so if you come to a non-https version of any page it should redirect to https. This adds a little bit to page load times, so it's still a good idea to update your bookmarks, but should help avoid problems with login cookies.