I keep getting these black screens

Only happens in League. Also, i noticed all the textures keep loading in poor quality despite my graphics settings, yet I open up a game like Fallout or Rust and it is working as per usual.

• Steps to recreate Black Screens:
• Out of game: Happens at random, usually alt-tab or ctrl-esc will produce a black screen and crash the client.
• In-game: it usually happens at the loading screen and promptly makes me restart league once or twice in order for the match to actually load.

Steps to recreate the low quality textures: Happens in game spontaneously, the textures will bounce from high quality to low quality and back to high at random.

I've been having these problems since yesterday. Windows 7 64 bit