iTunes 12.3 for Windows 10 x64 Hangs after AirPlay

I am really trying to solve this. I see 7 people said "I have this problem too" when I inquired last month, but no suggestions.

I have invested thousands in AirPlay speakers in my home - Bose, JBL, and iHome - and I use iTunes to listen to music. I can load iTunes and listen to music fine - all day - but if I stop the music playing and start it again, iTunes is frozen. If I try to quit iTunes, it's frozen - i have to use Task Manager to end the iTunes process.

If I use iTunes to download app updates and sync my iPhone, that works (though the iPhone connection times out - I have to plug it in within a minute or two of starting sync, or it can't find device). But in that case, iTunes does quit normally. It only hangs if I have listened to music.

New info using the Task Manager features.

When I load iTunes fresh after a reboot, Task Manager's "Analyze Wait Chain" shows "one or more threads of iTunes.exe are waiting to finish network I/O", and lists one thread waiting. That's before I do anything, just load it.

If I start to play music, the "Analyze" now lists 3 different threads that iTunes can't complete... two new ones appear below the original one. The music does play.

If I try to quit iTunes, "Analyze" now shows an additional thread on top, with a child thread, with the other 3 below.

The thread numbers are different every time, so I don't know what they mean. Is there a way more detail about a process thread? I think there was in Windows 7.

All of the above is unaffected by adding exclusion rules for all of Apple's processes to my antivirus program (Kaspersky AV 2015), as well as closing KAV completely. I have tried compatibility modes, and full uninstall/reinstall of all Apple components in the "correct" order - none of there worked. I am also seeing issues with "distnoted.exe" hogging CPU use, also widely reported.

Anyone know how to use the info above to get closer to solving this? I wish Apple would use some of its immense resources to support Apple lovers who also use Windows - there are lots of us!