Hi David,
It turns out the short answer is: Name your SubVI so that it doest not have the word About it in.
The following KB describes how to replace the default LabVIEW help with your own custom About screen:
How Can I Add an "About" Screen for an Executable Built with the LabVIEW Application BuilderAs far as how this impacts your application there are two options for the behavior of the About LabVIEW menu option. If you would like to leave the default LabVIEW about screen intact, all you will need to change in your current VIs is the name of the about.vi. If you name it to anything that doest not have the word about in it, the VI will no be run when the About LabVIEW selection is made.
The reason it would run but not close properly before is that the VI was loaded in memory and waiting to run as a SubVI in your main application. If you would like both your Help>>About selection and the About LabVIEW selection to point to the same VI, you will need to call the SubVI in your application dynamically so that it is not automatically loaded into memory. More information on one way to call a VI dynamically is available in this tutorial.
Calling a VI by ReferencePlease note that you will need to add the VI as a dynamic VI under the Source Files tab of the Application Builder.
Scott Y
NI