My League Doesn't Like Me

Hey everyone, I'm new to the forums and I need help with my LoL client. My game will work and proceed as to anyone else's client but when it comes to the loading screen and getting into a game it doesn't react normally. I'd be able to get into a queue and pick my champion and wait for the timer to continue down, but as soon as the screen goes black for that 2 second wait for the loading screen, my game tabs out and I'm unable to click it as it just keeps tabbing out. Also about 3 minutes into the game (As my friend says), I've tried reconnecting and it was a success but as I have the same problem, it tabs out but I can still hear the music and call out as well as the commentator. Help anyone?