Folders no longer reliably indicate read or unread.

When I tried the "Mark all as read" style link on the main forum page at the bottom, I got this page:

Has been going on for about a week, this error was new today. The main forum page also makes me look like I am not logged in, while clicking on any other sub-forum shows me as being logged in. I am unable to log in any further, and I have tried deleting all cookies and signing back in a few times.