Check the SSL settings: * Tools > Options > Advanced : Encryption: Protocols You can check the <b>ssl</b> and <b>tls</b> prefs on the about:config page. If any ssl or tls pref is bold (user set) then right-click that pref and choose "Reset" to reset the pref to the default value.<br /> Paste this regular expression in the Filter bar at the top of the about:config page: *<b>/security.*ssl|security.*tls/</b> *http://kb.mozillazine.org/about:config ---- Start Firefox in <u>[[Safe Mode|Safe Mode]]</u> to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance). *Do NOT click the Reset button on the Safe mode start window or otherwise make changes. *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes