In a game as the Zulu, on one turn I'm making 150 gpt then the next I'm losing 90 gpt and lose all my gold in my treasury. Here's the file of the turn just before it happened. I went back to the last available auto save (I have it set for every turn) and I got it again but a few turns later than it had happened last. I'm using the mods: Better trade screen, and Better Fog of War. You might need the fog of war one to make it work.