Program crashes when closing the last or only diagram.
Certain fast computers crash when the user closes a diagram.
This is a timing issue. The program is attempting to update the menus at the top of the screen based on information in the diagram. Unfortunately, on some fast machines, it tries to do this and finds that the diagram is already gone.
This bug require an update to version 6.502 at minimum. Select Help / About Intersection Magic and check the web for updates.