You may have ad / mal-ware. Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up. -------------- '''[https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/ Adblock Plus]''' {web link} Blocks annoying video ads on YouTube, Facebook ads, banners and much more. Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable). '''[https://addons.mozilla.org/en-US/firefox/addon/adblock-plus-pop-up-addon/ Adblock Plus Pop-up Addon]''' {web link} Adblock Plus Pop-up Addon extends the blocking functionality of Adblock Plus to those annoying pop-up windows that open on mouse clicks and other user actions. Forum; '''[https://adblockplus.org/forum/ Adblock Plus Homepage]''' {web link}

It sounds like your Firefox installation got taken over by malware. I'd suggest these steps: * [[Troubleshoot Firefox issues caused by malware]] * [[Refresh Firefox - reset add-ons and settings]]

https://malwaretips.com/blogs/ads-by-capricornus-removal/