I started facing this problem recently where the favicons which should be showing adjacent to the URLs, have disappeared and only gray globes are showing. I searched online and found this article where it is made clear that Mozilla deleted all favicons and only gray globes, gray padlocks, green padlocks or gray exclamation marks are shown. https://blog.mozilla.org/ux/2012/06/site-identity-ui-updates/ http://www.californiality.com/2012/07/mozilla-firefox-deletes-favicons.html I went through this page - https://support.mozilla.org/en-US/questions/933863#answer-357481 , which made it clear that for major websites, a green padlock should be showing . Even then, when I use Firefox, major websites like google.com or youtube.com are showing gray globes instead of green padlocks. I tried updating Firefox from 14 to 16.0.1 (which has been debugged by Mozilla and is fit to install and run - http://www.bbc.com/news/technology-19917466 ) I scanned the Mozilla folder in Program Files with and antivirus. I found this add on which restores Favicons, but am not sure about it. - https://addons.mozilla.org/en-US/firefox/addon/favicon-restorer/ . I really think there is a trojan or virus which is causing this and am really concerned about the security of my PC and personal information. Please, someone help me out.