PDF's are blank in Preview

I hope this is an appropriate place to post this question...
I have come across some PDF files that when opened in Preview are blank. The number of pages will be correct, but each page is blank. I can open these PDF's just fine using Adobe's Acrobat Reader, however I prefer to use Preview for its speed and simplicity. Does anyone have any idea why some PDF's are blank when opened using Preview? I want to note that one of the PDF's that I tried to open recently did not have anything special about (no forms, no extra JavaScript), it was just a plain old PDF. Any ideas?

A form has to be saved in Preview in order for it to be corrupted, not merely opened. What OS is used when opening a corrupted PDF in Reader/Acrobat doesn't matter.