Try see if this happens in safe mode: *[https://support.mozilla.org/kb/troubleshoot-firefox-issues-using-safe-mode Firefox in safe mode] Maybe your localstore.rdf is corrupted, try unhide the hidden files and folder, go to your profile folder, close firefox, delete or rename the localstore.rdf file and restart Firefox. *[http://kb.mozillazine.org/Show_hidden_files_and_folders] *[https://support.mozilla.org/kb/profiles-where-firefox-stores-user-data Profiles] Also: *[https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems Reset Firefox] *[https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles Create a new profile]