What kind of things does the bug do?
It freezes the game. If I can't close the game after a few seconds my computer will get a full freeze and I can't do anything without a reboot.

How does the bug work?
I tried it a few times and it's only (I think) in the multiplayer of the Windows 10 Edition.
I wrote a few messages and if I like to get a few older messages with the up and down
keys on my keyboard, my computer will get a freeze and I need to reboot them.

Thank you for reading this report!

Yours faithfully,
Paul