You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Adblock Plus {web link} Blocks annoying video ads on YouTube, Facebook ads, banners and much more. Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).

Adblock Plus Pop-up Addon {web link} Adblock Plus Pop-up Addon extends the blocking functionality of Adblock Plus to those annoying pop-up windows that open on mouse clicks and other user actions.

Forum; Adblock Plus Homepage {web link}

Unforunately, the screenshot did not post successfully. If the above reply doesn't help, you could post it in a reply to your own question:

https://support.mozilla.org/questions/1088311#question-reply

Please cut out or blur any sensitive content in the image before attaching it to your reply.

Hi jscher2000,

Thanks for your prompt response. Screenshot of the problem has been uploaded. Hope it would further clarify my problem.

Hi, thanks for the screenshots. As FredMcD suggested, this is a malware issue, so please try working through Remove zeroredirect1.com pop-up ads by Malware Tips.

Note that not all removal programs will detect all malware, so you may need to run several or all of them.

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