'''http://kb.mozillazine.org/Issues_with_Firefox#Downloading_opening_or_saving_files''' https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

It is possible that security software (anti-virus, firewall) is causing problems. Try to disable security software temporarily to see if that makes a difference. Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that helps. *http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/ *http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10