I have In-Game Trouble Please Help!

Hello there dear Summoners, So recently i've been having some techincal difficulties and i cant do anything,So first of all i log in to my league of legends client and everything is going smoothly but after i play a game or 2 my computer freezes in game and i hear a loop of the game in the backround meanwhile having a black screen and the only solution that there is is to shut down my computer. So i thought it might be hardware problem or something and i went to a computer technician and he changed my hardware,after i got the laptop i installed league and played some games but the same thing happened again. So here is my graphics card, i have a NVIDIA GeForce 330M with the resolution of 1920x1080 and it's a Windows 7 Laptop with intel core i5. So all i want from you guys is to help me because this thing has been bugging me for quite sometime and i always get 20 minute low priority queue for 5 games and it has really impacted my account because after all i dont want to get Banned or Suspended i need your help :(