I think it is interesting to note that Microsoft has removed any mention of Managed DirectX in the Microsoft DirectX SDK (November 2007) release. There is no longer a .chm file for managed code; there is no "managed" subdirectory under the "samples" directory and the sample explorer utility no longer has a "managed" check box for filtering. Looks like its time to give up on C# for DirectX applications. In early October I sent an email to firstname.lastname@example.org describing what I think is a bug in buffer notifications using c#. I included a demonstration program showing the problem. Briefly, it seems that notifications in the output buffer are generated when the currentWritePosition reaches the notification point instead of based on the currentPlayPosition as documented. As of 11/3/07 I have had no response or even acknowledgement of receipt of my email. If you want to learn more about this apparent bug, you can read the thread here: http://forums.microsoft.com/msdn/showpost.aspx?postid=2361599&siteid=1&sb=0&d=1&at=7&ft=11&tf=0&pageid=0 There is some discussion by others in the thread questioning if the notifications work correctly in C++/Win32 environment. This is a major problem for me. I at a minimum am faced with rewriting my DirectX related code in C++ and there is some question that this will solve the problem. Any knowledge of issues related to this that readers here might have would be greatly appreciated.