I had a situation where the web interface for Pingplotter went wonky and stopped displaying the graph part for all targets. I tried to re-start the service and it failed. I then killed the Pingplotter process. I started the service. After it was up again I noticed that quite a number of targets before had disappeared. I saw this same kind of behavior before when I rebooted a server running Pingplotter as a service. Overall my impression is it seems like it's unclear when and why it saves the target configuration but losing the targets as I have seen under the two circumstances outlined is not good.