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 v9.0.1 installed on Microsoft Windows 7 (64 Bits).