I came across some very odd rendering when trying to view a PDF file that needed to print out. I was wondering anyone has come across a similar problem before or has any ideas as to what might be causing this. PDF when viewed on OSX 10.7.4 - Preview version 6.0. I've tried opening the file in Skim but that doesn't work either. PDF as it should be, and as Chrome renders it in browser, but not if I download it onto my machine. Illustrator complains about "an unknown imaging construct" when I open the file, but renders it fine nevertheless, Photoshop doesn't have any problems either.