I've just upgraded to Windows 8. When I drag particular png (large in size) files in to my project, they appear as in the image.
<img src="https://dl.dropbox.com/u/10196246/Image%20Scaling.JPG" border="0" />
Testing the same project on my Windows 7 machine, the image is scaled all the way across the layout.
Capx
dl.dropbox.com/u/10196246/ImageSaleErrorWin8.capx