Other pages of yours contain enough text for the gallery in the bottom not to get into the bookmarks HTML (as a message body in the email bookmarklet, which is an extract from the page text).
Anyway, if you might not have the technical knowledge to identify the problem, you could try to deactivate certain plugins and see what happens and then make other wild guesses.
Looks like a bug in your social bookmarks plugin (it doesn’t escape special HTML characters), not an NGG problem. Try adding some more paragraphs of text to that page as a workaround.
