Wouldn't hurt to drop an email to support@stardock.com with your debug.err attached.
For older versions of GalCiv2 the file may be in C:\Program Files\Stardock\Totalgaming\GalCiv2.
If this is a Dark Avatar report, you'll find the file in C:\Program Files\Stardock\GalCiv2\DarkAvatar instead.
If you are running any of the newer expansions, it will be located in the My Games directory of My Documents in a folder corresponding to the newest expansion you are running(for example: Documents\My Games\GC2TwilightArnor).
Be sure to copy the debug immediately after the problem occurs; if you start the game again, the debug will be erased and recreated for the new session.