This isn't *exactly* what you're asking for, I don't think, but you can set up your maximum samples to hold in memory (Advanced option, auto-save tab, "maximum samples to hold in memory") to approximately the number of samples you collect during the day. The last save of the day (since you're doing it every 30 minutes) would basically have 24 hours worth of data that way, and the sample count would stay low enough that you shouldn't have any performance problems. You might even want to use a number that gives you a few hours from the previous day - so you don't have to look at 2 days worth of data when the problem occurs at midnight (ie: make the save file include 28 hours, or just a bit over 24).<br><br>Feel free to comment on how well this solution will work for you.<br><br>As for the problem not saving when Ping Plotter is signaled to close by Windows shutdown - I'll have a look at this, I'm imagining how this could happen.<br><br>