Have you installed one of the Firefox 4 beta builds and used the same profile folder (location where user data is stored) the beta build and Firefox 3.6.13? Firefox 4 beta moves the home icon , if you then revert to Firefox 3.6.13 it will not move the home icon back. You can move the icon back by following the instructions in this link - https://support.mozilla.com/kb/How+to+customize+the+toolbar If you have installed the Firefox 4 beta you should not use the same profile folder if you will be switching between the 2 versions, that can lead to problems. Instead create a new profile for Firefox 4. The following links show how: * http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows * http://kb.mozillazine.org/Shortcut_to_a_specific_profile * http://kb.mozillazine.org/Testing_pre-release_versions