That doesn't make sense the browser doesn't do popups. That comes from the site only. The Browser doesn't send bills that sounds more like malware infected computer.

Is this a bill from the website you were on, or just something that does not identify itself? Go to the [https://addons.mozilla.org/en-US/firefox/ Mozilla Add-ons Web Page] {web Link} (There’s a lot of good stuff here) and search for what you want. a good ad blocker. ----------------- You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.