If there are problems with updating then best is to download the full version and uninstall the currently installed version. Download a fresh Firefox copy and save the file to the desktop. * Firefox 4.0.x: http://www.mozilla.com/en-US/firefox/all.html * Firefox 3.6.x: http://www.mozilla.com/en-US/firefox/all-older.html * Uninstall your current Firefox version. * Do not remove personal data when you uninstall the current version. Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer. * It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling. Your bookmarks and other profile data are stored elsewhere in the [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder] and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox. ---- It may not be necessary to create a new profile, so first try if it works with your current profile and if not then create a new profile. You do not need to create a new profile, that is not necessary for this issue. ---- See also: * http://kb.mozillazine.org/Software_Update (Software Update not working properly)