Please go to C:\Program Files\Stardock\Totalgaming\GalCiv2 (or wherever you installed the game at), open the debug.err file you find there in notepad, and copy/paste the contents into a post here. If this is a DA report, you'll find the debug in C:\Program Files\Stardock\Totalgaming\GalCiv2\DarkAvatar instead. This will give us some technical information that can help troubleshoot your problem.

Be sure to copy the debug immediately after the error occurs; if you start the game again, the debug will be erased and recreated for the new session.

Note: If running on Vista with DA 1.6b2 or later, the debug.err is now located in My Documents\My Games\GC2DarkAvatar.