Form Elements vanish in Access 2007

I am teaching a class Access 2007, relational database development and some of the students have a strange problem. When developing their forms in the Form Design view all appears fine in design view, but when they try to use the form there is nothing on the form. All the elements vanish, but are still there in design view.

I have only recently converted to 2K7 and wondered if anyone out there had encountered this or a similar problem before as I am baffled by it!

Many thanks in advance to anyone who can save my sanity.