Ranked Leaver Warning Forced me to Leave

I was about to play my second ever game in the ranked queue, and the first in probably over a year. A helpful reminder regarding the penalties to leaving popped up, and when I clicked the "x" to make it disappear, the entire league client window became opaque and would not let me type or select anything, although the cursor still moved. I thought that maybe, when the time came for my champion select, the screen would unfreeze, but this was not the case. I even tried exiting the client by using the "x" in the upper right hand corner, but this too failed. Left with no other option, I ended up force stopping the program and eating the penalty. I just thought I would share this annoying irony here.

EDIT: Happened again without the leaver notification, client window just frosted over.