That message is characteristic of a web application firewall that sites use to ward off bot and denial of service attacks. It may appear when your request is considered suspicious, or if your IP address has been used for an attack recently. As a starting point, try clearing Cached Web Content: [[How to clear the Firefox cache]]. You also could test in Firefox's Safe Mode. In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" Help button > Restart with Add-ons Disabled * (menu bar) Help menu > Restart with Add-ons Disabled and OK the restart. ''Both scenarios:'' A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement?