''uninstalled/reinstalled Firefox, still no back/forward arrows for navigating tab history'' Reinstalling Firefox almost never solves anything. see https://support.mozilla.com/en-US/questions/851574 which covers customization, corrupt local_store.rdf, and locked or damaged places.sqlite You might try creating a bookmark backup and restoring that as opposed to renaming/deleting the places.sqlite file that was be a last resort where you lose all of your browser history.