If no-one else is having this problem, care to share your settings with me?
I don't have that issue with my AppleTV, at least not regularly.
The AppleTV AirPlay functionality has been pretty flaky for me generally, however, with the most recent software updates to the device. Mine decides to stop playing audio from a variety of apps suddenly and seemingly without cause. Some things that might help, until Apple fixes their device software:
* Using wired ethernet to connect the AppleTV to your network instead of Wifi. OSX has had trouble with Wifi reliability since 10.9, though it seems to be much better with the recently released 10.10.3 (but those fixes have not yet made their way to the AppleTV software).
* Rebooting the AppleTV. There is a magic remote combo to do this, but I find it is usually easiest just to unplug it and plug it back in.
* Make sure your Wifi network is relatively free of interference. OSX provides some nice tools for diagnosing noise in a Wifi network:
http://tidbits.com/article/15158https://support.apple.com/kb/PH18565?locale=en_US* I probably wouldn't buy one right now because everyone expects Apple to release new AppleTV hardware in June. Still, the third-generation AppleTVs seem to be way more stable with AirPlay in my experience. If you have an older one, they did drop the price on the third-gen box to $69 recently.