Loading Screen [CRASH]

Ever since around Patch 4.21, I've been having occasional(once or twice a week) loading problems when playing normal (non ranked) games. The loading screen will start up like normal and my loading percentage will get to 100% (with around 44 ping). The other players loading screens will also get a 100% or to around that area, then the screen will black out and exit to my desktop. My cursor will be the LOL Hand-pointer and I am unable to force close the application through Control-Shift-Esc, Alt-Tab, etc, forcing me to restart the computer and reopen League and reconnect. Ive been able to reconnect and join the game without any problems from there until recently, when the problem began happening more frequently. Today the aforementioned problem occurred and I rejoined relatively quickly and stayed through the end of the game. After this I got a warning from LeaveBuster stating that I had been afk, despite the fact that this problem had occurred multiple times before and I had never gotten the warning until now. I am unsure if this has anything to do with it, but the champion I play the most is Yasuo.