Windows Media Centre Extenders such as Xbox 360 allow TV shows, music and other media to be streamed from a Windows Vista PC (Ultimate in my case). I experienced Event ID 107 from program the extender connection program McrMgr:-
"An unauthorized window was detected while running the Windows Media Centre Experience, 'SymNotifyWnd', with file name ''."
This has happened half hourly since upgrading to NIS 2009 on 5th November 2008. Microsoft TechNet says: -
"This error can occur when a user interface (UI), such as a dialog box or notification, is trying to appear when Windows Media Centre is started on the Extender. This is referred to as an unauthorized window because UI other than the Windows Media Centre UI is not allowed to be displayed on the Extender."
NIS 2009 is attempting to send dialog boxes or notifications to connected Windows Media Centre Extenders resulting in the Event ID 107 messages. The Xbox connection is terminated and has to be re-established and the media reselected before the show can continue.
Symantec One Click Support spent 5 hours connected remotely to my PC yesterday monitoring for the problem but it did not occur. Perhaps this fault cannot be reproduced over remote monitoring if Symantec redirect dialog box display to the remote session? They recommended the reinstallation of NIS 2009 which has changed the problem manifestation (it is not happening half hourly at the moment) but did not eliminate it as Event ID 107s still occurred. They happened every 1 to 2 minutes for several hours, for example, but this stopped once I acknowledged a dialog box on the Windows PC(sorry, can't remember what it said).
I suspect that the reinstall may have caused the NIS firewall to relearn the ports used to connect the extender and the traffic from the extender therefore no longer triggers NIS to attempt to send the same dialog box to the Xbox at half hourly intervals. However, as Version 16.0.0.125 (no update here yet) has the capability to send dialog boxes to the Xbox and cause disconnections I believe the disconnections will continue to be possible.
I do not know if this is the same issue but there is an acknowledged NIS 2009 problem where Silent Mode (which suppresses most of alerts?) does not detect full screen applications that are launched on a secondary display monitor. There is no present solution for that.
I therefore believe that NIS 2009 is capable of causing seemingly random disconnections of Windows Media Centre Extenders. I accept that the trigger for these disconnections could be the misconfiguration of the firewall, the presence of a security risk somewhere on the host PC or similar. My issue is NIS 2009 behaviour is not compatible with “UI other than the Windows Media Centre UI is not allowed to be displayed on the Extender”.