Look like your software is not ready for international :
See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.
************** Exception Text **************
System.FormatException: Input string was not in a correct format.
at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
at System.Number.ParseDouble(String value, NumberStyles options, NumberFormatInfo numfmt)
at System.Double.Parse(String s, NumberStyles style, NumberFormatInfo info)
at System.Convert.ToDouble(String value)
at PerformanceComparison.Form1.RefreshTurnPlot()
at PerformanceComparison.Form1.RefreshPlots()
at PerformanceComparison.Form1.AircraftList_ItemCheck(Object sender, ItemCheckEventArgs e)
at System.Windows.Forms.CheckedListBox.OnItemCheck(ItemCheckEventArgs ice)
at System.Windows.Forms.CheckedListBox.LbnSelChange()
FYI in France the décimal separator is the " , " not the " . " like in lof of countries.
Plus there is a trouble when resizing the window, the blue bitmap with the 51 is moving too.