ITunes 11 Stops Responding to Bonjour Discovery Multicast Broadcasts, Why? This stops the the Apple TV 3 from being able to start a new stream from the home share and the iPad remote app can no longer see the home share too.

Question

I'm having an issue where my Apple TV 3 and all our iPads periodically seem to loose connectivity to an iTunes home share on a Windows 7 PC.  Using a network protocol analyser on the PC I have identified that the point of failure corresponds to the ATV3 sending a bonjour discovery request and getting no reply from iTunes.  Why the ATV3 'forgets' where the home share is is possibly another issue but the root cause of the failure is that iTunes, or more specifically the mDNSResponder service, is not responding to the UDP multicast port 5353 broadcast discovery packet sent by the ATV3 or iPad.  The mDNSResponder service does start responding again after iTunes is restarted thus making the home share accessible once more, however, this frequent drop out is unacceptable and often happens after only a single TV show has been watched from the home share making the solution unworkable for a family, we simply cannot be restarting iTunes constantly it ruins the user experience completely!
The nature of this failure indicates that the ATV3, the iPads, the host PC and network are all working correctly and the point of failure here is the lack of response to the bonjour discovery protocol with the net result of either a spinning 'connecting to home share' message or the home share just disappearing from the computers section.
If there is a configuration fix for this please let me know as I haven't located a fix!  Otherwise this seems very much to be a code flaw in iTunes 11 or the mDNSResponder and I would appreciate some input from Apple!  Going on other questions in these forums it would seem the problem is not limited to Windows PCs but also Macs too.  NB: This is not a TCP issue, when the ATV3 or iPad knows the IP of the iTunes server all works flawlessly, it just periodically they seem to refresh the list of home shares and at this point they loose the information about the home share they have just been using because of the non-response to the UDP multicast discovery broadcast packet, that is arriving at the host PC and isn't being blocked by the firewall.
Many Thanks!

Answer 1

In my case there was no import from a former mac.
My problem (at least mine) is that no app that offers media sharing works properly. Neither itunes home sharing nor AirVideo nor EyeTV sharing.
So I'm pretty sure that this is network issue.
Adding another user on my mac and sharing a new library works not also. But sharing from another laptop in my WiFi works. So this has to be a network issue on my mac, not only my user, but an issue of the whole system.
But I'm not willing to reinstall MacOS X for that if I don't have to.