[Ben]

It's a known vbulletin issue caused by the session table (database that keeps track of logins) filling up. How long the site's down is usually however long it takes me to get to a computer and empty it. Once we're up and running on a new server, I'll check if there's a way to automate this.

The reason a different browser sometimes works is because this actually only affects users previously logged in. So clearing cookies will also allow you to access the forum.