I have sent you the document to have a look at.
And, based on jeff Shenk's suggestion, I opened a brand new document, copied over the stuff on the page I had been showing and the disappearing did NOT reoccur in the brand new doc.
I am thinking that maybe it is an issue with the page size. The page size for the document is not a standard page size but is a custom defined page size and maybe that is at the core of the issue.
thanks very much all round.
I got the document and it definitely it the problem that happens with some large documents in Pages. Earlier we have seen the similar behaviour in Word Processing documents. In your document you still can move the objects but you only see the outlining about the last 3 centimeters on the page. As Jeff suggested copy the content over to a new blank template is ften a good solution.
I also ha other problems after while but reopning the document got rid of them. It seems that when a document has a lot of information Pages has problem handling them.