When you launch a new tab, you get a webpage on a Television Fanatic site? Normally the only way to replace Firefox's new tab page is an extension. You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either: * Ctrl+Shift+a (Mac: Command+Shift+a) * "3-bar" menu button (or Tools menu) > Add-ons In the left column, click Extensions. Then cast a critical eye over the list on the right side. All extensions are optional. If in doubt, disable. Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step. Any improvement? Also, perhaps it's a good time to scan your system: https://www.malwarebytes.com/antimalware/mac/