Launcher wont load

Just purchased Minecraft Java for my son on Windows PC. Minecraft Launcher opens and it seems to work but when he clicks "play".. the Mojang screen starts loading but then crashes. Ive gone through the forum and have the game output open. All I get is this:

Process crashed with exit code -805306369

 

I can't get the Mojang screen to load the game fully. I've also tried using it as Administrator and also tried the configuration settings. It just wont launch the game.