You may have an unwanted extension that is displaying those ads. Try this: Disable ALL nonessential or unrecognized extensions on the Add-ons page. Either: * Ctrl+Shift+a * orange Firefox button (or Tools menu) > Add-ons In the left column, click Extensions. Then, if in doubt, disable or remove. Usually 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. ---- If the Remove button is not available, then usually that extension was installed externally and needs to be removed through the Windows Control Panel, Uninstall a Program. Clicking the "Installed on" column heading will group the items by date so you can spot items that snuck in as part of a bundle. To mop up invasive software, you also can use the tools listed in this support article: [[Troubleshoot Firefox issues caused by malware]] ---- Any luck? If you identify the culprit, please name names.