When you open the Manage Add-ons dialog box on the Tools menu in Microsoft Internet Explorer, some installed add-ons may not be listed. Therefore, for example, you may not be able to select an add-on that you want to disable.
This issue occurs because, during the installation of certain add-ons, a flag is set in the registry that prevents the add-on from being managed through the Manage Add-ons dialog box.
More Info : http://www.go4i.net/modules.php?name=News&file=article&sid=101
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