Having the same issue. I tried with a clean folder, administrator account, removed mods, no 3rd party antivirus. Before this happened, my game had the ''There is a problem with your game's setup. Please reinstall your game.'' error, which was most likely caused by removing Gshade. I managed to fix that error and my game worked for some time, however for whatever reason it won't open now. Just reinstalled the game again (this worked the last time), I will update if it worked. Providing a dxdiag.
Update: clean game works after reinstalling. I'm just a little worried it's a temporary fix and that I'll have to reinstall it every time I want to play.
