When using the NortonInternetSecurityBF plug-in in Safari 6.1 browser, I have problems opening PDF files. They either open corrupted, or completely fail to open. When I disable the plug-in and restart Safari, PDF files will load normally. I also use the same version of the NIS plug-in with Firebox ver 25 without any PDF document issues. The NIS plug-in is version 1.7.0f37, and I'm running under Mac OS X 10.8.5 (Mountain Lion). The problem seems to be related to Safari only, since Firebox has never failed to download, open, or display PDF files. Any suggestions would be greatly appreciated.