Black screen in game

Just got a brand new computer and League seems to run fine, at least until I get into the game. Randomly at times, the game will freeze for about 4-5 seconds, the screen will go black and the next thing I see when I come back in the game my champion is dead. I've almost gotten reported a few times cause of this issue. I have tried playing the game in Borderless and Windowed and the same thing has happened. [slayer-jinx-unamused] I've spoken with Riot Player support for almost a week now and have followed every step they have given me in order to fix this issue. This seems like a League issue. It doesn't matter whether I'm in a regular match or in Practice Tool, the freeze happens regardless. I have NO idea what is causing this or why. I have updated drivers, uninstalled, and reinstalled my graphics card drivers. If anyone knows what is causing this issue and how to fix it, it would be greatly appreciated. Thanks!