Have you tried just using the built in updater to update firefox? [[Update Firefox to the latest version]]

Hi Mazzy If there is an issue with update or permissions the better, quickest and safest way is to download and install firefox: 1. Download a copy of the latest firefox from http://www.mozilla.org/en-US/firefox/all.html 2. '''''Trash''''' the current Firefox application to do a clean install. 3. Install the version that you have downloaded. Do not select to remove your personal data, 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 or other personal data. see also: [https://support.mozilla.org/en-US/kb/install-firefox-mac?redirectlocale=en-US&redirectslug=Installing+Firefox+on+Mac Installing Firefox on Mac] remember also Firefox 16 (and 16.0.1 of course) is the last version of Firefox that works with Mac OS X 10.5 : [https://support.mozilla.org/en-US/kb/firefox-no-longer-works-mac-os-x-10-5 Firefox no longer works with Mac OS X 10.5] thank you Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.

Solved. Thank you.