REGEDIT

HKEY_CLASSES_ROOT\CLSID\
    {7f9609be-af9a-11d1-83e0-00c04fb6e984}
        = Fax File Viewer
        InProcServer32
            = faxshell.dll
            ThreadingModel = Apartment        

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved
    {7f9609be-af9a-11d1-83e0-00c04fb6e984} = Fax File Viewer