If you get this nasty little sucker as an error message on your MOSS installation when you´re trying to add a new page based on a page layout:
Server Error in ‘/’ Application.
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.
Parser Error Message: Only Content controls are allowed directly in a content page that contains Content controls.
Line 104:<html xmlns:mso=”urn:schemas-microsoft-com:office:office” xmlns:msdt=”uuid:C2F41010-65B3-11d1-A29F-00AA00C14882″><head>
Line 105:<!–[if gte mso 9]><xml>
…chances are you have a <asp:content> tag instead of <asp:Content> in your page layout (aspx file). Worked for me at least.