Hi, Please check if this happens in [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode]. Safe mode disables the installed '''Extensions''', and themes ('''Appearance''') in '''Tools''' ('''Alt''' + '''T''') > '''Add-ons'''. Hardware acceleration is also temporarily disabled - the manual setting is '''Tools''' > '''Options''' > '''Advanced''' > '''General''' > [https://support.mozilla.org/en-US/kb/Options%20window%20-%20Advanced%20panel?as=u '''Use hardware acceleration when available''']. All these settings/options/add-ons can also be individually or collectively disabled/enabled/changed in Firefox normal mode to check if an extension, theme, option or hardware acceleration is causing issues. Disabling/enabling hardware acceleration, and some types of add-ons in normal mode may require a Firefox restart. [http://support.mozilla.com/en-US/kb/Uninstalling+add-ons Uninstalling Add-ons] [http://kb.mozillazine.org/Uninstalling_toolbars Uninstalling Toolbars] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.org/en-US/kb/Options%20window Options] If you have security software (antivirus, firewall etc.) installed, you can try deleting all existing instances of Firefox and related files in all the different configuration areas/modules of the security software. Instead create new allow/trusted rules for Firefox and its related processes. Even otherwise the security software may also ask again when Firefox is started and you can try to allow/trust at that time. Please see [https://support.mozilla.org/en-US/kb/Firewalls this]. [http://kb.mozillazine.org/Firewalls AV/Firewalls Configuration]