Client freezing at 100%

For the past 3 months at least, when loading into a match, the client will occasionally freeze at 100%. The client freezes, CTRL+ALT+DELETE doesn't matter, CTRL+SHIFT+ESC doesn't matter, none of it matters because none of this interrupts anything anymore.

Let me clarify: it's impossible to close it when this happens.

Spamming the windows key will (sometimes) eventually bring up the start menu where it's then possible to restart the computer. Usually I elect to hold down the power button and shut it down because this is the fastest way to not ruin everything for myself and 9 other people. This has happened to me in normals, ranked, ARAMs, and TFT. In a game like League, this is not acceptable. It's also not acceptable that it hasn't been addressed as a known issue to Riot as I am far from alone in experiencing this. In fact, it's happened to most of my friends atleast once. Also, it sucks getting reported, being unable to receive honors (and exp?), and losing out on rewards as a result of something that's not our fault, but yours.

Anyway, I hope someone with a job reads this. Thanks.