Hi, not a Mac person here so if you can figure out from my Windows instructions what is needed then great. uninstall Firefox. Then Delete the Mozilla Firefox Folders in C:\Program Files and C:\Program Files(x86) Then restart system. Note: your Firefox Profile is saved. But you should make a back up before you do : *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer Reinstall with Current Release Firefox 58.0.2 with a Full Version Installer *https://www.mozilla.org/firefox/all/ Note it is possible that the Profile is the issue. Create a new profile as a TEST to check if your current profile is causing the problem. *https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data *https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles *http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem. Never work with original files. *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox Please let us know if this solved your issue or if need further assistance.