Deleting the files "AdobePDFViewerNPAPI.plugin" and "AdobePDFViewer.plugin" worked BUT then Safari couldn't display pdf files embedded on web pages.
I found putting "AdobePDFViewerNPAPI.plugin" back fixed the display problem.
What I didn't know was that now when viewing a pdf, there is the pdf menu that becomes visible when mousing to the bottom of a page on the displayed pdf. Using it instead of the old Safari method for saving pdf's on web pages solved my problem.
Thanks to C D R (above) for the tip!
I'm on Snow Leopard 10.6.8.