I have been working on a Silverlight Navigation application which uses LINQ to query an XML data source and has been working without a hitch until I added a control to the landing page. All other pages which worked fine were loaded from the navigation service Once I added the control I got a page not found error! (The page is there) and If navigated to, it works as expected. What happens, it that I closed the error Modal dialog and then clicked on another page, then navigate back to the landing page...