Allakhazam main menu mouseover not workingFollow

For some reason I can't figure out, the dropdown submenus that appear when doing a mouseover on the main menu items (Items, Quests, Places, etc..) will not stay open unless I keep the mouse specifically on the main menu item. If I move the mouse to select one of the submenu options, the submenu vanishes. This only happens in Firefox (using 3.07, no upgrades available atm), not in IE, but I'd rather not use IE. Anyone have a suggestion on what might be causing this behavior?

The WoW site.