Thank you for your advice Patv and usually I just stick with the Visual Editor. I’ve been uploaded a combination of text and images to the page, adding to this over the months, so I’m not sure if that is what is causing the problem. However, even if I just use the visual editor to make my changes (without consulting the HTML View) and then click ‘Preview Changes’ most of the page will disappear. What is strange is that this has never happened before when I’ve previously added some images and text to the page. I wondered if it was a bug with the latest upgrade of WP? Would be great if you have any further advice.
