We have a Windows Service which runs on 2003 Server. It opens a source Word document using the Word Interop and then does some stuff with it. It also does likewise with Excel and PowerPoint files. 

Recently we've tried moving this service onto a Windows 2008 Server machine and are having real problems with it.

COMException at Microsoft.Office.Interop.Excel.Workbooks.Open
COMException at Microsoft.Office.Interop.Word.Documents.Open

I get the above exceptions when the windows service is running on 2008 Server. Looking at the Task Manager, the application does load ok, but then closes again shortly after. 

I've read things about Vista and Server 2008 not having a Session0 anymore, and have tried changing the Office DCOM security properties accordingly, including changing the identity of the user running them to Integrated but to no avail. 

Does anyone know if this is possible at all? This is a fundamental aspect of our system and so we need to be able to do this. 

Thanks