A suggestion if you get the "content file locked" CoreCompiler.bat error
Steam is nutty
from
GalCiv3 Forums
Friendly help...
I got this error:

I found a post with a similar problem on Steam, and followed their advice. I reinstalled the game files, updated my virus protection (AVG), and restarted the computer. I don't know which step did it, but one of them did.
Good luck!