[Crash] After Champ Select the game black screens

After the Champ select screen the game opens and it black screens for a while and then the Hand/gauntlet thing pops up and my game doesn't respond properly this happens very frequently aka after almost every champ select sometimes it only last a few seconds then the pre game screen pops up but recently its been taking up to 5 minutes and then the game wont let me alt+f4 nor will it let me alt+tab but when I ctrl+alt+Del it works but it makes me have to press reconnect then it does it again all while my team remakes because im not there and I get leaver buster for it and it frustrates me to the max extent please fix I hate leaver buster its useless because wait time for Queue is already so long I hate waiting another 20:00 minutes for something I cannot control. This happens on more than one account and I keep getting Leaver busters on both of them.

Here are the links: https://vimeo.com/268540903 https://vimeo.com/268541451