Screen/Client Locked

During champion select I picked my champion switched from ignite to heal and my screen locked. It looked like the brightness on the client dimmed (the screen was darker) and I couldn't click on anything. I waited for the game to start and I was able to play no problem. After the game ended the screen was still locked in this state and I was still unable to click on anything. I had to force shut down league in order to close the game (I couldn't click on anything) and reloading fixed the problem.