I wish I had made a screendump of it but I will try to explain.

During my 5th campaign scenario, I was informed that one of the allied races had built their spinning facility.
At that time my screen turned totally purple with me only being able to read all text of the buttons I could press.
Pressing escape even the savegame screen showed pruple with text. I could still save a game.

Due to the purple overlapping all other screen, including starmap, planets, ships etc the game could not be continued

Quitting the game and reloading my saved game solved the problem. Quitting did not trigger any error reports.

GalCiv2 version: 1.0D-1
System: windows XP
CPU: P4 3.6 GHz
Graphic card: Geforce 7800 GT/Dual/512MB