It appears that there is no way to navigate from Mozilla's front page to where you can find older releases. Here is how it's done. Google for "firefox older releases" and click on (what is today's at least) top link which is nominally to http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/ but turns into http://releases.mozilla.org/pub/mozilla.org/firefox/releases/ From there select the appropriate release directory (e.g. 3.6.13/), then the OS (win32/), then the language (en_US/). Then download the executable (Firefox Setup 3.6.13.exe) not the .asc file. Run the executable. At one point you will be asked to click on the "upgrade" button to finish the install. Click on it, even though you are in reality implementing a downgrade. Do not click on the Google-listed link to http://www.mozilla.com/firefox/all-older.html because that does NOT take you to a place where "all-older" versions are accessible, despite the link name.