If you make sure to have a backup of all the three needed settings (user name/email and password and Sync key) then you can easily set up Sync again in a new profile. You should always backup the Sync key anyway. What problem do you have that you want to reset Firefox?

The browser takes about 30-45 seconds to start. The other sync computer is not colocated so setting up sync will be difficult.

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 ---- You can 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 If the new profile works then you can transfer some files from an existing profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox