To add more input to this, I just add an occurence where it closes some instances based on an action. I have five instances opened. When I tried to launch a new instance by clicking on one of them which allows me to open a URL into a new window, if you try to close the upcoming new window before it finishes, this can also create the same behavior. By having do that, four instances got closed just like that without any warning. Suggestion: never close a window in progress ...lol