The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
Please go to client > top left menu > Show logs folder > logs > sort by Date Modified. From there, drag/drop the most recent game log file (should be of the game that just froze/crashed) into here so those that can help (not me) have that data to look at.
