ATV 2/AirPlay audio drop-out issue

I am having a problem with audio streaming using Airplay. With my Apple TV 2, if I stream from an iTunes library (AirPlay) to my ATV 2, after some random number of songs (sometimes 3, sometimes 10, sometimes 30--I can find no particular pattern), the streaming stops. I have tried this on both my wired network, my wireless network, and a mixture of client/source networks. I have tried it on a 27" iMac, and a 15" MacBook Pro, both up-to-date with OS releases and iTunes releases. On both sources, the music continues to play, and ATV icon continues to show in the bottom right of the iTunes window. I should add that the first several times I attempted this, it worked for hours on end with no problems.

I have restarted my router, restarted my switch, restarted the ATV 2, restarted the Macs, all multiple times, and have tried to switch around the ports on the router/switch. Right now, my ATV 2 and my iMac are plugged into the same D-Link 8-port GB switch. As I have more HDMI sources than ports on my TV, I have tried connecting the ATV 2 to both the HDMI switch and directly to the TV, with no difference in stalled ATV 2 audio streaming outcome.

To compound matters, thinking I had a dud unity, I went to the Apple Store and purchased another unit. Again, the first time or two I used it, it worked fine, and then the NEW unit began displaying the same behavior.

I have an older ATV 1, and I can stream to it until the cows come home and I experience NO problems.

Any thoughts?