LoL problem when playing with a laptop

I'm playing on the garena server, fyi. Every single time I'm done with champion select and it goes into the loading screen, the League Of Legends border in the middle shows up, and then it crash my game. And after it crashed, I can't get back in after like 15 mins and it always causes me to lose every single game. Although I'm just playing normal, I wanna have fun with my friends but I can't, due to this constantly happening. Anyone knows why, or any solution to this annoying problem?