This has been happening since the redesign earlier this year.
When I click an email notification that there’s a new reply or new post in the beta category, it takes me to an error page.
Not sure if this is a setting that you can control, but it’d be great if it could prompt for login rather than saying the page doesn’t exist. Since there’s no header on this page either, it’s a little cumbersome to actually log in and get to the topic.
Also, did you folks change the cookie durations when you did the redesign? Seems that something about the expiration time of the cookies is off (even when I tick “remember me”, it doesn’t seem to do so for very long).