I was having the exact same problem. I bought the GOG version today (v 2.5.0.11) and couldn't get it to run at all. It simply crashed with a runtime error before loading up. After uninstalling, reinstalling, checking drivers, etc. I simply tried to run it out of the GOG Galaxy launcher and it loaded right up. It took a while to import it into GOG Galaxy, so maybe it was applying some sort of patch, but problem solved.
Death to Steam! Long live GOG!