Please have a look at this post. [https://support.mozilla.com/en-US/questions/839203 https://support.mozilla.com/en-US/questions/839203] Good luck

Norton released an update patch for Firefox 5.0 on Tuesday 06-21 when Firefox 5.0 was released. ''(versus taking their normal six to eight weeks)'' Some Norton users have reported that the toolbar may not work if the Norton patch was installed before Firefox 5.0, instead if after Firefox 5.0 was already installed. http://community.norton.com/t5/Norton-Internet-Security-Norton/Update-Available-Firefox-5-0-Compatibility-Release-for-Norton/td-p/478160 http://community.norton.com/t5/Norton-Internet-Security-Norton/Norton-Toolbar-for-Firefox-5/td-p/475704/page/16