ARAM preparation period issue (Client issue?)

I wanna play ARAM and got a match. But during the preparation period before game. My client display was in the correct page (where you can choose rune page & masteries , etc) for literally 1 second, and then it jumped to some other page incompletely. So my display (the LOL window) just went black and can't do anything. I had to quit, then I got the 15 minutes punishment. BUT ITS NOT MY FAULT. Please explain.