Crashing only in rankeds

Hi. So after 6 years of league of legend, I am kinda done. I wasn't playing that often anyway. I tried playing several ranked games and I got complete system error crashes. For some reason, when I had to restart my pc and login into client, my login details were gone, region was changed. I couldn't login forever. My friend asked them not re-make. And then I get error again. I can't even make screenshots because everything is stuck, I cannot alt-tab and even if I close the error, I cannot close the game. Never have I had so many issues with client, specially playing in ranked. It's like you're doing this on purpose.. Gosh.