Simply the integers from server-side sent out to client side.
Client side didn't recieve the integers nor the packets.
Making all the shit flipping out.
And at the same time.. they both sent packets and caused the client to confuse and was programmed to settle it's self.
Basically it did what it was suppose to do... not crash. but it saved itself by removing chat and all the buttons.
Interesting glitch, I use to get a glitch to my minimap where it was just black with yellow(npc) and white(people) dots but nothing like what you just showed me.
Lagg Glitch, I used to get it when I would log out, it would display the 'Walk Here' 'Follow ______' 'Trade with _______' then I'd haft to restart login page to get back on -_-