After installing Yahoo Messenger on your computer (even with the custom method) when you open Firefox and visit add-ons manager, you can notice Yahoo Application State Plugin installed there. This plugin has nothing to do or no-way related to functioning of Yahoo messenger on desktop, you can disable it there by choosing ‘Never Activate’, but let us see how we can remove it.
Removing Yahoo Application State Plugin in Firefox
1. Visit about:plugins url in the browser
2. Note down the path of the plugin file npYState.dll and close Firefox browser, navigate to ‘C:\Program Files\Yahoo!\Shared ‘and delete it.
3. When you open Firefox and check installed plugins, Application State Plugin won’t be there.
Have you found this tip useful? Let us know in the comments.