The "Add-Ons" screen should tell you whether the Norton 360 toolbar is disabled because of incompatibility with Firefox 4. If it is then you have two options: - you can install the "Add-On Compatibility Reporter" plugin. That will let you enable the Norton toolbar even though it is not supported, but then the toolbar might not work as expected (and it might introduce other problems as well). - or you can wait for Symantec to release a compatible version of the toolbar (recommended)