Prior saved .pdf sometimes has blacked out content. How can I prevent this?

Question

I use Mac OS 9 Maverick, read email in Mail.app and Yahoo.Mail, switch between Safari and Firefox for browsing (because Safari does not allow Flash videos to appear on pages).  When I want to save an email or an html file or report as .pdf, I use Command-P and select Save As PDF from the Print popup.  Normally, I can go back years later and read the .pdf document in the Home File I filed it in using Adobe Reader.  Sometimes, however, when I open a .pdf file--and I cannot tell prior to opening it--all of the content has been blacked out.  It is as if someone redacted the document after filing it, which I don't do. 
How can I prevent these redactions?  The content being blacked out varies from extremely personal and important health files to simple email correspondence I want to save.  Sometimes I have paid for a document and have to contact the publisher to send hard copy via USPS due to this problem.
What am I missing here?  Do I need a specific plug-in?  Is there a way to retrieve the blacked-out content from my computer stored file?
Peter

Answer 1

This forum is only for discussions on the forums themselves. You should post your question in the apropriate product forum,
http://forums.adobe.com/community/shockwave
if your ptoblem is with Shockwave, or
http://forums.adobe.com/community/flashplayer
if it affects Flash Player.