I have the same problem as Mindful_Viking.

Purchased the Crusade DLC, installed it.  While it was installing Microsoft VC, the job just hung.

Tried again, it says it succeeded.

Run GalCiv3, got the "choose a game" menu, pick GalCiv3, window disappears, disk churns a bit, then NOTHING.

No game, no windows with error messages, nothing.

Uninstalled GalCiv3 completely, rebooted, complete re-install.

Same result.  NOTHING.

Any ideas, because I'm getting pretty frustrated.  Can't play GalCiv3 at all now.  Crusade has broken it.