To which version do you want to update? To the latest Firefox 3.6.11 version? Did you try via Help > Check for Updates? If that doesn't work then do this: * Download a new copy of the Firefox program: http://www.mozilla.com/firefox/all.html * Trash the current Firefox application to do a clean (re)install. * Install the new version that you have downloaded. Your profile data is stored elsewhere in the [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder], so you won't lose your bookmarks and other personal data.