New screen, game won't work

So I recently bought a 4k 27UD68-w. I installed the drivers and it works ok to browse the web, watch streams,etc and just general use. However I go into Overwatch and even if I reduce the definition from its native 3840x 2160 to the recommended ( which is 2560x1440) it keeps effing alt-tabbing me to the desktop. Wtf? It’ll be working fine i’ll be happily playing and then boom, off we go to the desktop. I try and alt-tab back in, screen goes blank like its loading, then takes me back to the desktop again. It takes about 4 to 5 alt tab attempts and me spamming a few keys to actually get back into the round I am playing.

My system should be able to run this, I have the latest Nvidia driver and I actually put the over watch settings on low as well. Any ideas?

Are you running this new monitor along with another monitor or is this the only monitor on your system. In the meantime, I recommend doing a full reset of the game video and audio settings by following the steps in the link below first: