Whenever you click on a link to go to a new web page, your browser automatically tells the new web site where you came from. This URL of the page you came from is known as the "referer" and is passed in a hidden part of the conversation between your browser and the web server providing the new page. This can be deemed to be an invasion of your privacy.

To disable referrer blocking, right click the NPF icon in your system tray and choose Block referrer and then choose No. This should resolve the problem you are having.