I've been having the same problem. I thought I fixed it moths ago with the htrt from the support page but I'm still getting data corruption issues with this game. That's why I have a leaver buster on my account. The first leave was because my laptops fan got jammed making the game unplayable so I had to figure out how to open it to get to the fan and what I had to do was remove the keyboard to get the screws underneath then I blew all the dust out of the heat sink and fan. 2 fps isn't playable. Then 2 games later, data corruption. I've contacted riot support and I force repaired but I'm still waiting to see if it happens again.
[zombie-nunu-bummed] if that didn't fix it, I'll try the hextech repair tool and repatch. If no then I'll do a full reinstall. If no then I don't know what to do.