I have done this before with MFC programs without a problem because I could set the class name. This is a no go with net except through a hack.
I cannot use the window title either because it is decorated. So FindWindow seems to be out of the question.
The net program uses a mutex to ensure single instance and I can get NSIS to detect it. However, I cannot get NSIS to tell the running instance to close from this.
So, any suggestions? Thanks people.