ProtectGoalSeek Property [Excel 2003 VBA Language Reference]
True if the user cannot modify chart data points with mouse actions. Read/write Boolean.
This property is not persisted when the file is saved. If you set this property to True and then reopen the file, it will no longer be set to True.
This example protects the data points on embedded chart one on worksheet one.
Worksheets(1).ChartObjects(1).Chart.ProtectGoalSeek = True
Applies to | Chart Object