Alt Tab crashed the client

twice now this has happened to me. I was in champ select, i told people what lane i wanted, and i alt tabbed back to chrome, and league started flipping out and blinking rapidly, i click on league and everything froze, i could still hear chat sounds but i couldnt do anything. then i alt tabbed again hoping it would fix it, instead league just went ENTIRELY black. I also hit CNTRL ALT DLT to see if bringing up task manager worked, but nothing. Twice now ive gotten leaver buster for their client crashing, kinda bullshit in my opinion, i get punished for their crappy work. Repair doesnt work. reboot on the comp doesnt work, this only happened today after the small patch came out. no point in giving a screen shot cause all of league goes black, no borders nothing.