Bugged Client

Can someone please tell me, why my client keeps bugging out, every time I try and go into a ranked game. So basically what happens is after the queue and lobby, the portion to where the game tries to boot up. my entire screen goes black and I can't get out of it. This doesn't happen all the time but it does it enough to where I'm losing a whole bunch of LP because of it and it's pissing me and my friends off because it's been doing it to all of us consecutively.

From a small indie company, I expect this neglectfulness but considering this is a multiple billion-dollar company, I honestly expect more and I'm disappointed.