Launch Dayz.
Have whatever conflicting firewall on.
Go into change server.
No game server will show up.
(This is the point where you can still kill it with task manager).
Now if you press cancel or on any other tab the game will hang and only way to get rid of it is to completely restart your computer.
If you disable the firewall servers will show up. If you connect the game will play fine up to the moment where you leave the server, at which point it will hang up completely as explained above.