In my April 8, 2004 blog I wrote a small doc regarding how to go about Solving the DriverInternalErrorException Exception that gets raised under cirtian circumstances when rendering in windowed mode. This is the responce microsft sent me ...
The following was received from the Managed DirectX development team:
No, it's not really valid, and no I don't believe we should create a bug for the issue.
Before the device automatically resets the backbuffer it raises an event (DeviceResizing), that allows you to cancel this behavior. It is up to the application to determine whether they want to allow the resize or not, not MDX..
You can read the original doc as well as microsofts responce here DX Resize