The main menu items no longer work in the CP after I upgraded to Firefox 4.0. It also does not work on Chrome, but does work in Safari and IE8/IE. When clicking a menu item, the submenu does not appear. This was reported to me by my client, so it is happening on multiple machines.
The version number is 2.0.2pb01. I know someone is going to recommend I upgrade to 2.1.3, but that is such a painful and error prone process that I would really want to avoid having to do it, especially since I will have to do it gratis.
Note also that I have many other EE installations, mostly 2.1.2 and 2.1.3. Although they work OK, I have noticed flaky behavior with the menus since upgrading to Firefox 4.0 - in this case, when I click a menu item and then move my cursor to the submenu it will disappear, almost as if it does not recognize focus. Sometimes it does it, sometimes it doesn’t.