Problem with menus in 3.1 – bug?

Hi all.

I recently tried to add a new taxonomy tag to a menu I have, and it just wouldn’t add – the spinny thing just kept spinning but it wouldn’t add. I then added it manually as a URL and saved the menu and now /wp-admin/nav-menus.php just shows a bullet point and nothing else. The source code of wp-admin/nav-menus.php is only:

<li id="menu-item-492" class="menu-item menu-item-depth-0 menu-item-issue menu-item-edit-inactive">
			<dl class="menu-item-bar">
				<dt class="menu-item-handle">
					<span class="item-title">

No matter how much I refresh or log out and back in, I still can’t access this settings page.

Everything else in the backend seems to be working okay still. The actual menu on my blog now only consists of bullet points, but no labels.

Help!