PHP Breaks Dreamweaver Layout

Hi guys,

I have built a site for one of my clients which they want to update themselves using Dreamweaver.

Its all looking great, validates as XHTML & CSS but when you view it in Dreamweaver in the php include files for the header, footer & menu break the layout view.

Does anyone have any idea why this might be and if theres a workaround because this is a bit of a nightmare for the client!

Thanks!