Hi, I have the same problem, but I need lots of try to have a succsessful client start. Today it took a few hours to start 2-3 box, the client pops up for a second and immediatley closes after the launcher's Start button. In the past half year I didn't have any problem with the client, or with the connection to the server.
I fully re-installed the game, even scan file, but it didn't help.