Problem creating .NET COM object from C++ application.

Question

Here are the facts:

1) I have a .NET application which contains a class which has an exposed COM interface.

2) I have several C++ applications which instantiate an instance of this .NET COM class.

3) All C++ applications can successfully create the COM object on my dev PC.

4) On every other PC, one of my C++ applications fails to create the COM object failing with error: "No such interface supported". The remaining C++ applications don't fail.

Questions:

A) How can the interface be supported on my Dev PC and not others for one particular C++ app? The executable files are exactly the same on all machines.

B) How can all my C++ applications successfully instantiate the COM object, but one can't. It is literally the same code reused in each application.

C) How can I fix this? Is there some config setting I can tweak?

Thanks.