How to Uninstall and Remove Windows Genuine Advantage (WGA) Validation Plug-In for Firefox (npLegitCheckPlugin.dll)

Microsoft had released a Firefox version of Windows Genuine Advantage Validation Tool (WGA), in the form of plug-in or add-on. When user tries to download WGA genuine Windows restricted software from Microsoft Download Center, user is prompted to download and install WGAPluginInstall.exe which will perform validation test on legitimacy of Windows XP or Vista installed.

WGAPluginInstall.exe setup install npLegitCheckPlugin.dll and nsILegitCheckPlugin.xpt into Mozilla Firefox program directory. If user enter about:plugins in the Firefox address bar and hit Enter, he or she will see the following information:

WGA-pluugin with file name as npLegitCheckPlugin.dll version 1.7.0069.2.

Unfortunately, Microsoft does not provide an easy way to remove or uninstall the WGA plugin for Firefox. For users who have installed the WGA validation plugin for Firefox, use the following hack to clean, remove or uninstall the plug-in.

Go to C:\Program Files\Mozilla Firefox\plugins folder, and then delete the npLegitCheckPlugin.dll file. Then, go to C:\Program Files\Mozilla Firefox\components folder, and delete the nsILegitCheckPlugin.xpt file (if you have use the trick to install WGA plugin for Firefox in other than default Firefox location, find the plugin in the changed folder). After deletion , the WGA plugin is removed, and user can confirm the deletion by using “about:plugins” command again in Firefox.