I have problems with modal MFC windows over 3dsMax.

I'm popping a MFC modal window over 3dsMax (I'm programming a plugin for 3dsMax, if you mind), so I can't click on any 3dsMax window button, because the modal window is here.

The modal window, by clicking on a button, then makes a .NET window appear on another application. The modal window is still there. (The communication between the plugin and the other application is done with COM.) The problem is the following: when the .NET window is closed, the MFC window seems to lose its modality. I can click on 3dsMax buttons and I don't want that.

Can you propose me solutions to this?