When you’re inside a thread, all the way at the bottom the forums are listed (it’s called “Forum Jump”), but clicking the link to go to a new forum doesn’t work. I haven’t tried all of them, but the several I did try took me to a page that said “Oops! That page doesn’t exist or is private.”
Hopefully this is the right place to report this 
This also happens if you click on “The Straight Dope” at the top of any page.
What’s even worst is that failed page doesn’t have the normal stuff at the top right – your avatar and the three lines, especially.
So you’re sitting on a page with just a handful of ‘new’ posts and ‘suggested topics’ (or something like that, I forget exactly) and if you’re not interested in them, there is no obvious way to get to the topic list of a category.
(Yeah, yeah. Memorize the key shortcuts. I’m old and my brain is creaky.)