The Norton Toolbar is now compatible with Firefox 24. We have released a Firefox 24 compatibility patch for Norton Internet Security 21.0.1.3, 21.0.0.100, 20.4.0.40 and 19.9.1.14 which is available via LiveUpdate. Please see the Firefox 24 Compatibility Update announcement for version details and troubleshooting any problems with the update.
Note: We have also released a fix patch for Chrome 30 [Still in Beta - 30.0.1599.37]