I am writing an app that is responsible for shutting down and replacing all instances of another app. I was doing this with EnumWindows, searching for the right window class name and sending a message that will cause it to quit.

WindowXP however has the option of multiple users being logged in at once. EnumWindows doesn't give me those windows that are on another login. So I can't shut them down. This obviously prevents me from replacing the exe.

Is there a way of notification across logins that anyone's run across or can you come up with something clever?