AppleTv suddenly has stopped syncing

My AppleTV has suddenly stopped syncing with itunes, reporing a "non-responding" error and suggesting I check my firewall settings. It has worked perfectly for over a year, I have changed nothing just before this problem and don't run the firewall software. This is completely out of the blue. Powering down and restarting the ATV sometimes will allow a sync to occur which will start off as normal but will always hang at the last item being synced. If I cancel out of this and recommence syncing I get the original error. Have seen similar problems reported on forums but with no definite solution. Repairing permissions doesn't work. Evidently deleting the ATV from iTunes and reconnecting is fruitless too. I'm running iTunes 8 and the second last ATV update - don't want to do a full ATV reset in case I can't update - it currently won't connect to allow me to uodate now.

Any Help much appreciated. Very frustrating as it was working perfectly until a week ago.

Richard