I have the latest Firefox on Windows 7. I've had this problem for over a month on many other websites, but not being able to download addons is probably the most significant that I couldn't circumvent. The following methods have failed: 1) Clearing all Cache/Cookies several times 2) The problem persists in Safe Mode 3) Resetting Firefox to its default sate 4) Uninstalling and Reinstalling Firefox (yet saving my Bookmarks) 5) Scanning with avast! antivirus 6) Disabling avast! firewall temporarily (and clearing cache/cookies and restarting Firefox) 7) Going to about:config... Javascript is enabled. I don't have this problem in Chrome. What's interesting is that #4 temporarily solved the problem, only for it to re-emerge a day later. Twitter was one of the many sites that didn't work before #4, yet now it does work. The "Secure Connection Failed" has so-far only happened when I clicked the text-link to download the addon. Otherwise, failing to load javascript and images is the main problem. Please help! I'm really attached to Firefox and I don't want to change to another browser. (Ironically, I just clicked the green "Automatically add" button underneath this form, and got the "Secure Connection Failed" message, and would have lost everything I just typed if not for Lazarus add-on...)