[zzz61831]

What if you don't provide NATed internet to Windows machines at all and only let specific apps to connect to it through manually specified local proxies and maybe some whitelisted routes. Because shutting down internet access doesn't seem to cause any freezes for me.

[LinuxBender]

Yes if you disable the internet it won't try to talk to the activity endpoint. You could probably trick windows into thinking the internet is always down. I don't know what else this might break, but the cleaner way is to do the registry changes.