My first thought is to rename your My Games\Galciv 3 folder, validate the game files in Steam, reboot your computer and start a new game. Personally, I was able to continue a saved game successfully, but if anything happened I was going to follow this plan, as a start. Next is that if you are still having problems with a new game, sounds like submitting a ticket (see the instructions in the support forum). Of course this plan will mean you are not accessing any of your saved stuff, but I try to be philosophical about that as it is a Beta. But the beauty of renaming your My Games folder is that, for example, if you have ship designs you should be able to copy those over , and so forth. But I wouldn't worry about that until I get it running again.
The short from would be to just validate the game files --- perhaps the patch didn't take. You might need to reinstall Galciv3 altogether. Just some ideas.