Having the same problem, but unlike above doesn't seem to be fixing itself. Haven't used the launcher before - had taken a break for some other games - and the launcher works with Offworld Trading Company. However, GalCiv3 just keeps saying it is preparing to launch, then going back to the launcher.
I tried validating game files (apparently all present) and rebooting the computer (didn't help). Even tried launching directly from the executable (which just launches the launcher).
Just got a friend of mine to buy this three days ago and is working fine for her, but not for me all of the sudden.