multiple current_menu_item on home page after upgrade to wordpress 3.3

Yesterday I upgraded from WordPress 3.2.1 to 3.3. After doing so, my menu (which was working previously) now has a problem whereby multiple current_menu_item and current_page_item styles are added to the custom menu items which have nothing entered in URL field.

The problem only occurs on the Home page; once you navigate to any other pages the menu works as expected.

I notice that if I add something into the URL field of the custom menu items through the menu editor, ie: #, that it now works as expected and doesn’t add the current_menu_item. Unfortunately, this is not ideal, as I don’t want these menu items to indicate to the user that they are clickable, as an anchor might imply…

Can anyone help me solve this mystery? I’m out of ideas and can’t work out what has changed in the upgrade that would cause this, especially since it only occurs on the home page!??!!?

The URL in question is:
https://monkeyhut.com.au