You can check the target line in the Firefox desktop shortcut (right-click: Properties) to make sure that nothing is appended after the path to the Firefox program.

What are your connection and DNS settings?

You can check for problems with the sessionstore.js and sessionstore.bak files in the Firefox profile folder that store session data.

Rename (or delete) the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox profile folder.

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Multiple_profile_files_created

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost and you will have to recreate them (make a note or bookmark them if possible).

Hey cor-el, thank-you for your detailed response!

I solved it a different way. I changed the Firefox history setting to 'never remember history' and the problem was solved. I'm not sure if simply deleting all history would solve the problem the same way, but for now it all seems good.

You can consider to use a second profile without Leechblock if you need to access pages that are blocked.

See:

• http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox
• https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles

You can add -no-remote to the command line to open another Firefox instance with its own profile and run multiple Firefox instances simultaneously.

• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile