Game freezes then says client, must close... then cant back into the game

It happened not only to me but my teammate last game and the game freezes for 2 seconds. Then closes the game out but the client still works but cant get back into the game. I tried restarting the client and it gives me the same error...... 10 minutes later the game is fixed but worried it might happen again since its not just me but few people. The reconnect sign had the maintenance sign on it.