It's because your address bar has history of both http and https links. Logins with http have been disabled because it sends everything like your pw through your address bar (more or less) Stored pages with http will land you on busted login, but clicking on a link inside such as the masthead or main forum will all have links with https and a functioning login You even might be logged in already after clicking because its possible to have different cookies stored for http and https (safety reasons) @Clutch you can fix this by forcing automatic redirect to SSL as a sitewide setting
I believe the redirect is now fixed on all browsers. HTTP should auto redirect to HTTPS. If you're having any issues still with the login, please let me know. I appreciate it!
