Solution:-

Internet Explorer

Open Toolbar:-

Tools → Pop-up Blocker → Turn Off Pop-up Blocker 

Set:-

            Turn Off Pop-up Blocker

Mozilla Firefox
 

Open Toolbar:-

Tools à Options → Content 

Set:-

            Block Pop-up Window → Uncheck

Google Toolbar

If you have installed Goole Toolbar, 

Open Toolbar:-

Google Toolbar Settings → More → Pop-up Blocker 

Set:-

            Enable Pop-up Blocker → Uncheck