Do these open regardless of what you're doing at the time? There is some malware which works outside of Firefox and sends URLs to Windows, which Windows opens in your current default browser. Some users with that kind of malware report that it starts up Firefox to open pages if it wasn't running. I suggest starting here: Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here. Then, try to "mop up" remaining issues with the scanning/cleaning tools listed in our support article: [[Troubleshoot Firefox issues caused by malware]]. Any improvement?