You can install the portable Firefox 3.6 version to access websites that do not work with Firefox 5+. *http://www.freesmug.org/portableapps:firefox#toc1 *http://sourceforge.net/projects/osxportableapps/files/Portable%20Firefox%20OS%20X/ ---- See also this article about how to install multiple versions on Mac OS X: * http://www.businessinsider.com/how-to-run-firefox-4-and-3-simultaneously-in-mac-os-x-with-multiple-firefox-profiles-2011-3 * http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox