Yep, I'm still having this issue constantly, I'm going to take Stuart's advice from above and disconnect the ethernet from the Cinema Connection Kit the installer put in place when my HR34 was installed ..
I'm going to reboot the HR34 and see how it behaves over the next few days
I have other computers on my home network, but don't have any DVR's plugged directly into my home network any more, everything is done via DECA and then I have the Cinema Connection kit hear the HR34. No media servers running or anything that should be putting out a lot of uPnP traffic .. we'll see
Turn off upnp.