Create a new profile as a test to check if your current profile is causing the problems. See "Creating a profile": *https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles *http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues Profile Backup and Restore *http://kb.mozillazine.org/Profile_backup *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

See if you can start Firefox in Safe Mode. You can use one of these to start Firefox in <u>Safe Mode</u>: *On Windows, hold down the Shift key while starting Firefox with a double-click on the Firefox desktop shortcut *On Mac, hold down the Options key while starting Firefox *Help > Restart with Add-ons Disabled *https://support.mozilla.org/kb/Safe+Mode ---- It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program. Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process. See: *https://support.mozilla.org/kb/Server+not+found *https://support.mozilla.org/kb/Firewalls *https://support.mozilla.org/kb/fix-problems-connecting-websites-after-updating