Torbutton default "Off" if last setting was off (v1.4.6.2)
Torbutton was toggled off when Firefox was last used, and the new update to Torbutton blocks toggling, causing it to freeze in this position.
From a user perspective, the fix is not intuitive. Right click the onion icon, go to Preferences, then uncheck the "Disable Toggle" option. Which of course negates the point of disabling toggling. I recommend a check to see if Torbutton is active before enforcing that as the default.