Word 2007 Documents.Open returns null in ASP.NET

Hi,In the following code the method Documents.Open returns null when running under ASP.NET, while running it in a console the code works fine. The computer is installed with Vista OS and Office 2007. The code works under ASP.NET on a windows 2000 server with Office 2003. (The website is configured with identity impersonate="true")Does anyone have any idea what is causing this?        Object missing = Type.Missing;        Application app = new Application();        Object name = @"C:\a.doc";        Object confirmConversions = false;        Document doc = app.Documents.Open(            ref name, ref confirmConversions,            ref missing, ref missing, ref missing, ref missing,            ref missing, ref missing, ref missing, ref missing,            ref missing, ref missing, ref missing, ref missing,            ref missing, ref missing        );        Object saveas = @"C:\b.doc";        objec ...