The mining starbase originally belonged to a civilization whose worlds flipped to my civ. Pirates took it over. When I attacked the starbase (to release the ressource) the battle menu was not visibly entered. I could heard the firing sounds but that was it. The game hung after that, I couldn't do anything else with it. Tried pressing the ESC key in case it was in the menu part at the end of the battle (even though it wasn't displayed) but no dice.