After upgrading to OS X Yosemite, Preview stopped displaying some PDF’s properly. When launching a PDF I would get a gray screen followed by a black screen. The only option was to hold the power button down to shut the machine down.
After searching the Apple Discussion forums and submitting a bug report to Apple, I finally stumbled upon the fix.
1. Go into Preview Preferences.
2. Select the PDF tab.
3. Uncheck “Smooth text and line art.”
That’s it! Problem solved.