Try download the latest version for your mac os, from : ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/11.0/mac/ 1. Download a new copy of Firefox program from the above link 2. Trash, if you have, the current Firefox application. 3. Install the new version that you have downloaded. If you all ready have a firefox version install, 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/Installing%20Firefox%20on%20Mac Installing Firefox on Mac] thank you Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.