Hello,

can you please try downloading and installing Firefox from this site

• https://www.mozilla.org/en-US/firefox/all/

also see: How to install Firefox on Windows

Moreover before installing a fresh copy please perform malware scan

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: Home Page:

http://www.microsoft.com/windows/products/winfamily/defender/default.mspx

• 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

• Troubleshoot Firefox issues caused by malware

Make sure that your security software isn't causing this issue.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full, unrestricted, access to internet for Firefox and the plugin-container process and the updater process.

Do a clean reinstall and delete the Firefox program before (re)installing a fresh copy of the current Firefox release.

• Download the full Firefox installer and save the file to the desktop
  http://www.mozilla.org/en-US/firefox/all.html

If possible uninstall your current Firefox version to cleanup the Windows registry and settings in security software.

• Do NOT remove "personal data" when you uninstall your current Firefox version, because this will remove all profile folders and you lose personal data like bookmarks and passwords including data in profiles created by other Firefox versions.

Remove the Firefox program before installing that newly downloaded copy of the Firefox installer.

• (32 bit Windows) "C:\Program Files\Mozilla Firefox\"
• (64 bit Windows) "C:\Program Files (x86)\Mozilla Firefox\"

• It is important to delete the Firefox program to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other personal data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall