Oh, THAT bug. It's actually not caused by your browser, it's caused by LQT being stupid. You see, when you add a comment, a thread gets bumped, which means its last modified timestamp is updated. But when you click on a link in recent changes, that link has a timestamp in it, and it only displays threads before that timestamp. But the thread you were trying to get to now has a newer timestamp, so it disappears. In your case, the url you refreshed probably contained a timestamp (the offset= part), and when you refreshed, the thread disappeared because I bumped it.