Hello,

Try start Firefox in Safe Mode:

• Firefox Safe Mode

You also can scan your computer, the problem can be a malware:

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

You may have an unwanted extension that is injecting inappropriate ads into sites. Try this:

Disable ALL nonessential or unrecognized extensions on the Add-ons page. Either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

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.

Does that get rid of the ads?

You also should:

(1) Check the Windows Control Panel, Uninstall a Program, click the Installed on column heading to sort by date, and carefully review anything that might have snuck in as part of a bundle.

(2) Run some supplemental malware scans. This article lists tools that other Firefox users have found helpful: Troubleshoot Firefox issues caused by malware