Disable popup blockers on the browser. Popup blockers stop new browser windows or tabs from opening. If your code's execution depends on an opening window or tab, instruct the user to remove popup blockers so the web page executes properly. To disable the blockers in Internet Explorer and Firefox, click the "Tools" menu option, select "Internet Options" for Internet Explorer and click "Options" for Firefox. In Internet Explorer, click "Privacy" and remove the check box next to "Block popups." For Firefox, click the "Content" tab and remove the check box labeled "Block Popup Windows."