I just reinstalled Windows 7 64-bit(for other purposes) and of course downloaded firefox 21.0 as soon as I could, but found that there aren't any of the options like there used to be(before the reinstall) when I right click the firefox icon in the task bar("Enter private browsing," "open new tab," etc.). As in this same question posted here: https://support.mozilla.org/en-US/questions/943198?esab=a&as=aaq I have checked for the Userchrome.css file and none exists. In the start menu properties "Store and display recent options...." has been checked(unchecked and rechecked). Also mucked around in the about:config with specific options mentioned in the above link, and nothing(all are currently default). I don't know if certain extensions can cause issues with this, but I currently have stumbleupon, Personas Plus, NoScript, and AdBlockPlus(which if I'm not mistaken were all on before the windows reinstall). Even just reinstalled firefox just on the off chance it might fix it, but alas it did not.