. Whenever you get a message / popup like that;

DO NOT USE ANY OF THE PROVIDED LINKS OR ANY PHONE NUMBERS ! !

Such messages are only Spam that could lead you to Fake Support. Not only can they damage or hack your system, they charge you to do so.

You can report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

Did you get your Firefox from Mozilla.org? If not, Remove It ! !

• 1 Download Firefox Full Installer For All languages And Systems {web link}
• 2 Uninstall Firefox from your computer {web link}
  DO NOT remove your profiles.
• 3 After, reboot the computer. Then run the full installer.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

The installer may have set up some preferences in your settings folder. Here's how you can create a fresh settings folder:

Create a new Firefox profile

With Firefox closed, start up in the Profile Manager using the Windows "Run" dialog (Windows key + R, or it's somewhere on the Start screen with all the tiny program icons) -- type or paste the following and press Enter:

firefox.exe -P

Click the Create Profile button, assign a name like Clean, and ignore the option to change the folder location. Then start Firefox in the new profile you created.

This should not inherit any problem settings. Does it work better?

At this point, you might need to:

• Import data from another browser

If there is still a problem, the program folder might be contaminated. More on that if needed.