itunes 11.1.4.62 breaks wifi sync

WiFi sync has been working fine here for years.

Installed iTunes 11.1.4.62 and it no longer works properly. Sometimes I can get it to do a backup and calendar/contact sync okay. I cannot get it to do an apps sync anymore.

What I see on the screen is that iTunes initially recongizes my iPhone 4s. When iTunes fails, it says it's looking for my iPhone, can't find it, and deletes it from my devices list.

I tried completely uninstalling all Apple software and reinstalling.

iTunes syncing via USB works fine.

When iTunes disconnects from WiFi, I can still ping my iPhone so there isn't a network issue.

Environment is Win 7 64 bit.

BTW, I have the WiFi photo app installed, and I can connect to the iPhone via WiFi to transfer photos using this app even when iTunes is failing. So I think this is strictly an iTunes problem.