Getting unexpected pop-up or overlay ads can be caused by an add-on, or by external malware, or by a change to your connection settings. (1) Check Extensions (A) In Firefox: Try disabling ALL nonessential or unrecognized extensions on the Add-ons page. Either: * Ctrl+Shift+a * "3-bar" menu button (or Tools menu) > Add-ons In the left column, click Extensions. Then, if in doubt, disable. Or if it's clearly crap, 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. (B) In the Windows Control Panel If there is no remove button on the Add-ons page, typically the extension was installed externally and can be removed through the Windows Control Panel, Uninstall a Program. If you click the "Installed on" column heading to group the entries by date, you may find some undisclosed bundle items that snuck in with some free software. Take out as much trash as possible. (2) Malware scans Our support article lists free tools other Firefox users have found helpful: [[Troubleshoot Firefox issues caused by malware]]. (3) Connection settings Normally Firefox piggybacks on your IE connection settings. You can change that (or malware might have changed it). To view and modify: "3-bar" menu button (or Tools menu) > Options > Advanced > Network mini-tab > "Settings" button Change to "No proxy" and see whether that makes any difference.