I'm having this same issue since the latest patch. I've tried everything cleared profiles, deleted my whole install, Cleared steam configs like the troubleshooter suggests checked all my drivers uninstalled all mods did windows updates. even tried dev branch and -nolauncher. nadda.
Running a haswell i7 with amd 2xx series gfx card with windows 8.1 x64
Managed to get it running by running it as admin now. setup both the .exe and launcher.exe as run as admin and now its back to normal. hope this helps you guys too
