Bill,

>I have added a mmMenuExtender (actually a subclass without any code other than to inherit the mmMenuExtender). My menu system has submenu items - this is where the trouble lies. All menus without a submenu work fine. As soon as I add a submenu item I get this error.
>
>'null' is not a valid value for 'stream'

Hmmm...I haven't seen this one before. Do you get the same error if you add a submenu to the MM .NET Windows Forms sample application?

Regards,