For Windows, usually you would download an integrated installer that extracts its own files and then installs them. Could you try the installer on this page (scroll down to your preferred language): https://www.mozilla.org/firefox/all/ The standard "Windows" version is 32-bit and works on all systems. The "Windows 64-bit" version runs only on 64-bit Windows and can't run most plugin, just Flash and Silverlight. Does that full installer work any better?