I have a node within a site than when you preview it give the following error

Exception Details: System.Xml.XmlException: '.', hexadecimal value 0x00, is an invalid character. Line 9, position 48.

Stack Trace: 

[XmlException: '.', hexadecimal value 0x00, is an invalid character. Line 9, position 48.]

   System.Xml.XmlTextReaderImpl.Throw(String res, String[] args) +163

   System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type, Int32& outStartPos, Int32& outEndPos) +5177111

   System.Xml.XmlTextReaderImpl.ParseCDataOrComment(XmlNodeType type) +90

   System.Xml.XmlTextReaderImpl.ParseElementContent() +5185172

   System.Xml.XmlLoader.LoadNode(Boolean skipOverWhitespace) +249

   System.Xml.XmlLoader.ReadCurrentNode(XmlDocument doc, XmlReader reader) +117

   System.Xml.XmlDocument.ReadNode(XmlReader reader) +78

   umbraco.presentation.preview.PreviewContent.PrepareDocument(User user, Document documentObject, Boolean includeSubs) +456

   umbraco.presentation.dialogs.Preview.Page_Load(Object sender, EventArgs e) +229

   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25

   umbraco.BasePages.BasePage.OnLoad(EventArgs e) +19

   System.Web.UI.Control.LoadRecursive() +71

   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3064

This is a published page with no changes. I can remove all the content out of this page and it will still give the same error so i'm assuming the error lies else where. I've replaced all the config files with clean versions. Deleted the umbraco.config file. The xml for the page has been run through aml parsers successfully.

What else could be the problem?