Windows 10 crashing computer while playing league

I'm not too sure what is affecting my computer, I recently updated to Windows 10, and my computer has been crashing and becomes irresponsive after tabbing out. I also noticed that when I disable windows defender, the frequency of crashes also reduces. My computer screen fragments and sometimes recovers, telling me the video card driver has failed and recovered. When I try to update the driver, it says it is unable to update for whatever reason. Also, when starting up my computer, it tells me Windows 10 has launched incorrectly, tries to analyze the problem to fix it, but then says it cannot find a solution. My computer crashed several times within a game, and gave me Low-Priority-Queue which is fricken annoying when I didn't disconnect or afk. Really pissed off right now, Haven't been able to find a solution to this problem. Any help would be appreciated