http://blogs.msdn.com/b/peterwie/archive/2006/09/15/650813.aspxUMDF defines all of its interfaces using COM interfaces, rather than the flat C-style DDI that the KMDF team used.  When kernel developers see this their first question is often "why did you do that?" and it's an understandable question. I had a longenTelligent Evolution Platform Developer Build (Build: 5.6.50428.7875)