I just finished a Galciv 3 game and encountered a minor bug I've never run across before. I was playing Terran and my influence building bases gradually let me take over another small faction (I think it was the Yor). They had a fleet of ships on their last planet and I watched as the rebellion status grew until the planet yielded to me. BUT, the ships did not leave the planet that was now mine, even though I could build and terraform the tiles. The remaining ships did not turn pirate, as normally happens, so I played a few turns. Nothing. When I tried to land a fleet at the last planet, the game gave me the 'Do you really want to go to war?" prompt and I said yes. After that, my fleet destroyed the ships on the planet and I finally got the notice "The Yor race has been destroyed". First and only time it's ever happened.