Some websites are blocking for showing their sites inside a frame of another page.
In most cases you can avoid this blocking by installing a small extension to your browser.
We recommend the following:
Chrome: https://chrome.google.com/webstore/detail/xframe-assassin/nigpljchmlcjkhbglkdimgaplklombph
Firefox: https://addons.mozilla.org/en-US/firefox/addon/ignore-x-frame-options-header/
