Game client crash (System Error Message)

Right after champion select, when it tries to load the game, my client will crash. I will get a System Error message - "A critical error has occurred and the process must be terminated." (Ill link the image when I figure out how) Force quitting the client will allow me to reconnect to the game again, but it does the same exact thing. Client tries to load, client becomes unresponsive, client crashes. Sitting around and waiting results in the exact same chain of events as well.

The problem for me doesn't happen every game, it happens around every 3 or 4 games, so I can't really plan for it. I have probably already been reported a dozen times over this problem in the past few days (I think, thankfully nothing has come out of them if I have been reported at least)

Started a few days ago, I have taken a few steps already to fix the issue. Reset the computer, did nothing. Have checked my firewall settings, League is not being blocked at all. Have turned off my firewall completely, same issue occured a few games afterwards. I have completely reinstalled League, same issue occured. I have shut down the entire game then reloaded it, again same issue. I have used the Hextech Repair Tool thing, a few times, still hasn't solved the issue.

At this point I'm pretty much out of options, and am getting super frustrated over this situation. Some help would be gladly appreciated.

Edit I usually use custom solo matches to test my games connection when my client has issues like this, this issue on the other hand has never occured while loading into a custom match, might be a coincidence, might be important, I dunno.