The Do not allow Windows Messenger to be run machine setting should be configured correctly. Allows you to disable Windows Messenger. If you enable this setting, Windows Messenger will not run. If you disable or do not configure this setting, Windows Messenger can be used. Fix: (1) GPO: Computer Configuration\Administrative Templates\Windows Components\Windows Messenger\Do not allow Windows Messenger to be run (2) KEY: HKLM\Software\Policies\Microsoft\Messenger\Client\PreventRun