Screen Freeze

Hi guys! There's a very annoying thing when i try to play lol for a few days. When i get into the game after 1-2 minutes my screen freeze for about a minute or half a minute. My mouse is working but i can't do anything in the game. After this 1 minute freeze I can move for a few seconds and freezed again. If you guys know any solution please tell me, cuz that's very very annoying. Thanks, Jacint014.