Constantly Freezing

Hi, I think this problem started happening after the last 2 updates. After the loading screen, I can't see the champions and the entire computer freezes (No keys (esc, window button, or alt+tab) work once it gets into this mode). Only solution I found that happens to work sometimes is forcefully restarting the computer. Even when I do this, the game freezes in the middle of the game, forcing me to restart the computer. Repairing league didn't work. From restarting my computer, I got the "afk punishment" from riot, which got me pretty upset. Please help, I can't play this game under this condition. Thank you.