Ahh, I think I know what the problem is.. when you come to the forum - you come in on http. When you login, the forum redirects to https. Cookies (such as the one for your login) that are placed during an https session are not accessible while viewing a site in http mode. This is a sandboxing measure for security. When you hit "login" up top, it takes you into https mode, the site accesses your cookie and then you're logged in automatically.
In other words - when you come to http://www.homebrewersassociation.org/forum/index.php
it should automatically redirect you to https
://www.homebrewersassociation.org/forum/index.php, but it doesn't