We’re running Discourse v1.4.0.beta10 +170 and a user recently noticed that if he was on the “Latest” page, and then clicked on the “Latest” button in the nav bar, there would be an infinite spinner. This works whenever you click on the nav bar link of a page you’re already on. The same applies for keyboard shortcuts.
You’re right @codinghorror. It isn’t a problem on Meta; it only seems to affect our instance at http://community.lsst.org. Maybe it’ll just go away with the next update or rebuild?
Don’t worry about it for now, I’ll re-ping if this is a legitimately persistent problem.