I'm running 12.10 and using the onboard intel graphics - reported as Intel ivybridge /desktop. My wife dowloaded the attached pdf file and it has a large black rectangle on it. I downloaded it from my 12.04 machine (sandybridge intel chip) and the black rectangle is not there. I copied the 'good' file from my Desktop to hers and (magically) the black rectangle appears. So it was nothing to do with the original pdf file she downloaded. For some reason, when this pdf file is placed on her Desktop it appears (viewed via nautilus, document viewer, gimp, etc) with a black rectangle. What should I start looking at to see what is causing his problem?