[CRASH] Game crashes every time I click outside of the loading screen

I play League on borderless windowed so that I could easily click in and out of League while I'm dead or waiting for something in-game. During the loading screen, I often move my mouse onto my second monitor and click on another window. After I come back to click on League while it's still loading, it crashes. My recent game left me with a Bug Splat every time I tried launching the client. The usual fix behind it is that I use task manager to stop all League processes and restart, but when my task manager started acting up, I couldn't do that. I had to restart my computer entirely and by the time I came back, the game was already lost with the enemy team hitting my nexus. I ended up getting an abandon notice after the game when it wasn't my fault at all.

In my case, I have a second monitor. Here's how it usually happens:

1. After Champ Select comes the loading screen.
2. With borderless windowed already on, I go to my second monitor and click something.
3. Click on League again while still loading.
4. Game crashes.

Happens every time I do this. Lost my most recent game and got an abandon notice.

Thank you,

Panoldark