Peter, there's something very strange going on within your file. For example if you delete all the text/images and placeholders from page 4 Analysis and preview or export the site it's still all there.

I'm pretty sure it's something to do with the way you've placed html in the placeholder on page4. It looks like a full html page source which a placeholder can't contain, your creating a page within a page. I believe the only way to do this is via an iframe. Someone more knowledgeable than me will be along shortly and tell me I'm wrong.