Looks like malware with a DLL that has a random name as the culprit.

• Firefox 40.0.3 Crash Report [@ i34xljav.dll@0x427d9 ]

Do a malware check with several malware scanning programs on the Windows computer.

• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware

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

thanks for reply, I already updated the windows defender and try to install "Malwarebytes" but there is run time error once install Malwarebytes. I also do full scan on Microsoft safety scanner and the result is no virus or malware detected

any suggestion please ...

Did you do a search for this i34xljav.dll file?

You can also search the Windows registry for this tile to see to what software it belongs.

Try to install a program in Windows Safe mode in case of problems.

You can use the MSConfig program or the Autoruns utility to see what software is getting started (be cautious with disabling services).

• http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx