Nope, I don't have network drives but just in case I've disabled network discovery and file sharing. We'll see what happens but I suspect it might not make any difference.
Regarding UAC, I've tried it on the normal setting, on the don't notify setting and completely disabled via the registry and it still does it. Also does it regardless of SmartScreen setting as well.
I can reproduce it easily. Play a song in iTunes normally, then watch a YouTube video then try to play a song in iTunes again.