I only have Dread Lords, but mine is located in My Documents\My Games\GalCiv2.
Each version of the game will have its own debug.err file in its respective folder. Post the one for the version of the game you are playing - just after a crash. The file is created fresh whenever you start the game and continually updates, so it is important to post the info just after a crash so we can see what was happening just before the crash.
You can open the file with Notepad, then 'select all', copy, and paste into the reply box.
The actual problem could be a memory issue or a hardware issue. You could be to a point where there is so much going on that you are overheating the CPU/GPU. Or perhaps it could be a memory issue if you are on a very large map and have a lot of stuff (ships, textures, opponents, etc). It could also be a mod that you are using, if you come to a point in a modded file that has an internal conflict.
