[CLIENT] My client freezes during Pick and Ban Phase of Ranked Games

This is really frustrating and and I'm not sure how to fix it. Several times when waiting in the lobby of a Ranked Game I wait for everyone to finish picking. At any sudden moment, my client freezes. Windows asks if I want to wait for it to respond, but after 15 minutes of waiting, nothing happens. As a result, I'm forced to close the client and restart it, finding that I have lost one of my provisional games. Just right now, I tried clicking the scroll bar in order to see what my team mates are saying and the client froze. I have now lost my final provisional game and on top, I have received a 30-minute penalty. Can anyone help somehow fix this? I'm not entirely upset about losing my game because, if I'm skilled enough, I know I can get back to promotion. But, getting stumped because of something I didn't do isn't fair.

Thanks.

-A Frustrated and Sad Summoner