The game freezes when is loading on 100% and twice in-game

Hello, I was starting to play two games a few minutes ago. Everything was normal as I logged in, queued, and prepared for the match in champion select. However, during the loading screen everyone's portraits loaded really slowly, and the game suddenly started without anyone reaching 100%. In my Shen game, the screen froze and I couldn't do anything at all (not even alt+tab), so I had to restart my computer. In my second game, I had a few seconds to level up an ability and buy items, but it froze again.

I'm not sure what the problem is. My internet connection is stable before, during, and after the freeze. My gaming pc is fairly new and never had problems before.

After the game is done which I played somehow I've got a warning that won't be tolerated in future. I just don't want to get banned to be honest.