Please update to version 19.0 and check your computer for malware and spyware.

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

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!

My current version of firefox is shown as 17.0.1 and update informs me that this is latest version so it seems v 19 is unavailable. I have malwarebytes installed and a run shows no malware.

Regards,

mnemo165

Firefox 19.0.2 is available here:
http://www.mozilla.org/en-US/firefox/new/

Ad blocker has been discontinued. Try Updated Ad Blocker instead.
https://addons.mozilla.org/en-US/firefox/addon/updated-ad-blocker-for-fire/

Although kaspesky 2013 is installed on my computer but this popup doesn't stop from appearing. i tried to deal with this problem by installing a program called SUPER AD BLOCKER. IT often works but the windows of firefox keep shivering when the popup try to appear. what can i do?

please go to firefox > addons > extensions & remove any suspicious entries (toolbars, things that you have not installed intentionally, don't know what purpose they serve, etc). also go to the windows control panel / programs and remove all toolbars or potentially unwanted software from there and run a full scan of your system with the security software that you have in place and different other tools like the free version of malwarebytes & adwcleaner.

Remove a toolbar that has taken over your Firefox search or home page Troubleshoot Firefox issues caused by malware