Noticed this today so posting it here.
My current page when loaded looks like this: http://i.imgur.com/bGQtP.png
Previously, when the page would load, it would somehow auto-correct, and the forum list would be higher on the page (though everything above it was still visible). You could see the navigation bar below the forum list. I think it has something to do with the size of the ad at the top, because once (today) it showed a smaller one and it looked the way it used to. It's not a big deal, I'll have to adjust to it, but if it's some kind of bug I'd want to let you know.
Using Firefox 11 and no add-ons, Windows 7.
Edit: Here's how it looks after it "shifts": http://i.imgur.com/CPMnp.png