> Have you properly re-set-up your portrayals in your load() method? Hm, yes. It calls setupPortrayals() as does my start() method. I tested also to create a checkpoint directly from the GUI and then reload it. If I quit and restart my GUI, also that checkpoint is black. But if I only quit the simulation without quitting the GUI itself, and then reload the checkpoint, the Portrayal shows my agents as it should be, but the display is frozen. I.e. if I unpause the simulation it runs but the Portrayal just shows the agents as they were after loading the checkpoint. axel