#1 - May 12, 2016, 10:03 p.m.
If your client is crashing (not disconnecting, actually closing and popping up the Blizzard Error Reporter window and everything) when you go to launch from the Battle.net App, you'll need to run the repair tool.
Open your Battle.net App, click on World of Warcraft on the left tab, then click the Options button and select Scan and Repair. Follow the steps to repair your client, and this should resolve your issue.
Again, this is unrelated to getting disconnected from the server or getting kicked back to the login screen.