Thank you for the extensive list :). "All the menu items" would also have been okay... however, they're all working for me. Can you provide more details about your environment, and make sure you've cleared ytour browser cache?
We have a redirection component that handles URLs from the old site, which we need to leave on for a few months until Google migrates its search results to the new URL scheme. However, I've seen a couple of times where the component mis-fires. Unfortunately, we also have aggressive caching on the site, especially for users who aren't logged in – so it's possible your browser/proxy/everything-else was caching the old response. It's just as possible _our_ upstream cache (we use CloudFlare) was doing it for a bit.
Hi. I'm new here but I'm having the same problem. IE 11 and Pale Moon 26 on Windows 10 Enterprise. Like Wes said, only Forum, Calendar, and Login seem to work. Flushing the cache did nothing but since I've never been here before, I'm not surprised.