Spectate mode isn't working!

I've been trying to spectate ranked games but whenever I try black screen pops up and after 30 sec. client crashes. My connection is fine. I can launch the game, I can play any mode, but when it comes to spectating I have this black screen problem for almost 4 days. Before that it was just fine. I know only one solution which is re-installing the game but I don't want to do that. Is there any solution for this problem?

P.S.: Also, sometimes spectate mode loses the connection on the main menu. A connection lost message pops up for no reason.