I have to stop and mention that your Firefox identified itself as version 15, which is ancient now. Did you install the current 38.0.1 release?

If "Yes", please see this article for steps to get Firefox to report its version correctly: How to reset the default user agent on Firefox.

If "No", please install Firefox 38.0.1 from this page (scroll down to your preferred language): https://www.mozilla.org/firefox/all/

Self-opening tabs can be generated either internally to Firefox by add-ons or externally by other programs directly a URL to your default browser. The add-on problem is much more common so... let's start there.

Here's my suggested procedure for tracking down and cleaning up bad add-ons. I know it seems long, but it's not that bad.

(1) Open the Windows Control Panel, Uninstall a Program. 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. Be suspicious of everything you do not recognize/remember, as malware often uses important or innocent sounding names to discourage you from removing it. Take out as much trash as possible here.

(2) Open Firefox's Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons
• in the Windows "Run" dialog, type or paste
  firefox.exe "about:addons"

In the left column, click Plugins. Set nonessential and unrecognized plugins to "Never Activate".

In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

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.

Any improvement?

(3) You can search for remaining issues with the scanning/cleaning tools 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.

Success?

yeah previously i was facing this problem with the latest version. there is no add on also i deleted the extensions along this i scan my computer for virus but nothing found suspicious.

Hi, jscher2000 has given good advice.

You really do need to update your very old version of FF, which is vulnerable to security attacks.

Note that not all malware scanners will remove all malware, so you may need to run all these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• 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. Windows 8 has antivirus built-in already.

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

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Finally, please run the SearchReset add-on.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

I already scan my pc through Microsoft security essentials but nothing found suspicious. Need your help in this regards. Thanks

Are there any extensions installed and enabled in Firefox?

You can check for recently installed suspicious or unknown extensions.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

You can check in "Windows Control Panel > Programs" for recently installed programs to see if anything from Conduit or any other suspicious software like Search Protect shows up.

• Control Panel > Programs > Programs and Features > Uninstall or change a program
• Click the Installed column to sort by this heading

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware