Bug introduced in 9.0.1 or earlier and persisting through 11.0.1 or later
When I try to export graphics as PNG, JPG and other rasterized formats using the right-click and choosing Save Graphic As..., if the notebook magnification is changed from 100%, Mathematica fails to export the image and returns the following error:
The specified setting for the option WindowSize cannot be used.
However this does not happen when Export function is used to export the graphic.

I think this is a bug.
I am using Mathematica 9.0.1 installed on Microsoft Windows 7 (64-bit).
Save Graphic As...notSave Selection As.... I think the two questions are related and your question is not duplicate. – M6299 Aug 05 '14 at 14:20