The lock symbol has been replaced with the [[Site Identity button]] in Firefox 4.0.x You can however reinstate it by downloading this add-on: https://addons.mozilla.org/en-US/firefox/addon/padlock-icon/?src=discovery-learnmore ---- Incidentally, you need to install the latest Adobe updates since the current versions you have installed expose your system to attack. * Update Adobe Flash via http://get.adobe.com/flashplayer/ * Update Adobe Reader via http://get.adobe.com/reader/?promoid=BUIGO * Update Java via http://www.java.com/en/ Here's the relevant Adobe security advisory: http://www.adobe.com/support/security/advisories/apsa11-02.html