Hi spnshacres, Without having more information on what you are describing it is really difficult to troubleshoot. Can you please describe the ad? Where does it show up? What does it look like? Is it on every page or just a single page? If it is only on one page, I'd assume it is probably not a Firefox issue. If it's something that you see everywhere, I'd try starting Firefox in [[Safe Mode]]. If you don't have the issue while all of your add-ons, extensions, and themes are disabled, you can try adding them back in one by one until you find the culprit. You should look at the [https://support.mozilla.org/en-US/kb/Troubleshooting-extensions-themes Extensions and Themes troubleshooting guide ] and the [[Troubleshooting plugins]] article as well. You could also try [https://support.mozilla.org/en-US/kb/Managing-profiles?s=create+a+new+profile&r=2&e=es&as=s#w_creating-a-profile Creating a new profile]. Hopefully this helps!