LoL crashing frequently?

I have experienced a problem with my game, a lot of times it would just freeze. My laptop was working fine , I could open and close everything except LoL and also it would stay on my screen all the time so I couldn't view other applications. Closing it neither worked, so what I had to do was restart my laptop entirely, open league, log in and rejoin the match. Well this process doesn't take long because I have a fast laptop but sometimes my team would surrender and they all report me for leaving, and that is the problem. I am scared to play league anymore because it might happen and I get banned... Does anyone have a suggestion to fix my problem?