Ever since the upgrade, my atv has been acting up. Sometimes, when trying to watch a movie, it will say not authorized to play this or unsupported format. Even when playing podcasts, it will say there are no podcasts on itunes. Any of these problems have occurred while trying to start a movie/podcast, or during a movie/podcast--they just stop. I have an airport extreme router set to n only, it has never given my a problem. I have itunes updated to the latest version and my files are stored on an external HD connected to my iMac that serves itunes to the atv. Before 2.1, I never had a single problem, now I can't even finish a single movie. Anyone else have this problem? Any ideas?