Running an application inside .NET MDI application

[Tulkas]

I am developing a .NET MDI application in C# VS2005.
One of the MDI client windows is running an MFC based application within the window (GPS navigation software).
This is all fine, but it seems that the MFC application overrules the MDI functionality of the .NET application. I can not minimize the MFC window, hide it or resize it without having the MDI parent dirty. When I open another "pure" MDI client window, it stays behind the MFC window. I have tried to resize, minimize, change z-order and about everything else I could think of through the user32.dll. Using [user32.dll] SetWindowPos with various parameters has given the best results, but I am missing the last functionality to get my MFC client window to act as a normal MDI window. When trying to hide the MDI form, the MFC application just terminates.
The MFC application is wrapped in a custom user control. This custom user control is then added to the MDUI form in my project.

I can post some of the code. But to me it seems that it is not the code, but the strategy that is wrong here.

So, any questions and ideas are more than welcome.

BR
/Tulkas