Install ublock origin from the addon store.

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe"

Does that URL show up in your home page setting? This article will get you to that part of the Options page: [[Startup, home page, tabs, and download settings]]. If the problem is not your home page setting, or if you cannot keep the setting on the page you actually want as your home page, there may be some malware on your system. <p>Here's my suggested procedure for tracking down and cleaning up bad add-ons and other hijackers. I know it seems long, but it's really not that bad.</p> <p>(1) Open the Windows <strong>Control Panel</strong>, Uninstall a Program.</p> <p>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. <em>Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it.</em></p> <p>Take out as much trash as possible here. If you're not sure, feel free to post program names or a screenshot of the list.</p> <p>(2) Open Firefox's <strong>Add-ons page</strong> using either:</p> <ul> <li>Ctrl+Shift+a (Mac: Command+Shift+a)</li> <li>"3-bar" menu button (or Tools menu) &gt; Add-ons</li> <li>in the Windows "Run" dialog, type or paste<br>firefox.exe "about:addons"</li> </ul> <p>In the left column, click <strong>Extensions</strong>. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions; the troublemaker might not be obvious from its name. <em>All Mozilla-installed extensions are hidden from this page, so whatever you see here is your choice and your responsibility to enable, disable, or remove.</em></p> <p>Often 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.</p> <p>Any improvement?</p> <p>(3) You can search for remaining issues with the <strong>scanning/cleaning tools</strong> listed in our support article:[[Troubleshoot Firefox issues caused by malware]]. These on-demand scanners are free and take considerable time to run. If they finish quickly and especially if they require payment, you may have a serious infection. I suggest the specialized forums listed in the article in that case.</p> <p>(4) Then finally if needed:</p> * Restore your preferred home page: [[How to set the home page]] * Restore your preferred default search engine: [[Change your default search settings in Firefox]] If your home page works in new Windows (Ctrl+n) but you get a different page at startup: '''''Investigate Your Shortcut''''' The Firefox icon can be set up to launch specific pages at startup (or more specifically, when you use the icon). To check whether that is set: First, open the shortcut as follows: * Desktop shortcut: right-click the icon, choose Properties * Pinned taskbar icon: right-click the icon, right-click Mozilla Firefox, choose Properties Windows normally will select the Shortcut tab. If not, go ahead and click the Shortcut tab. You'll see the Target highlighted. On 64-bit Windows, that usually is no more and no less than the following: "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" If anything follows after that, try clearing it out. After OK'ing the Properties dialog, you can test right away to confirm that Firefox now launches only your home page. Either: * double-click desktop shortcut * right-click pinned taskbar icon, click Mozilla Firefox Success?