When you go to the bookmarks pulldown menu at the top of the screen, the menu window that opens is much wider than previous browser versions. often stretching the full width of the browser window itself. In addition, once the cursor opens a bookmarks folder in a contextual side menu, you cannot go back to the main pulldown menu. It sticks there. You have to move the cursor up though the TOP of the contextual menu to free it to close the menu window. Simply moving the cursor back to the original menu does nothing -- the contextual menu sticks open as the active one. It will often take several attempts to land the cursor on the bookmarks folder you want to open before the cursor will hit it without opening other nearby folders, getting stuck in the process. I can't just move the cursor to what I'd like to open. (Cursor is functioning normally in all other apps and windows.) All other menus are fine. This occurs only with the bookmarks menu. Machine is an Imac dual core 2.25 running Leopard 10.5.8. Firefox is version 5.0. This behavior is repeatable on both a fresh download of FF5 and on the upgraded 4.0 to 5. Does not matter if launched in full mode or safe mode with no plugins -- same menu bug. All plugins are updated, including Download Helper, Flash, Shockwave, Silverlight and a few others. They all pass the plugin tests. This menu bug happens every time the FF browser is opened. No exceptions. Would sure love to have version 4 back until this bug is fixed, but I can no longer locate it on the Firefox website. As it currently sits, the browser is virtually unusable. :-(