After a lot of hit and trial, I did find out the cause of the issue to be an Add on. This add on is "Sound Frost". Which suspiciously, don't have any information on its details page, except the URL: *SoundFrost.org.
*i.minus.com/jgwOsw7MtMbYY.jpg
Scan result of the URL from
Virus Total reports that two scanners, Dr. Web and Sophos have identified the site to be malicious.
So beware FF users about this add on. Gave me quite a trouble. And now I am having trouble uninstalling the add on. I can only disable it.
