A Lisp Monitor window also appears when you start Common LispWorks. This is actually a separate process which shows you the state of the Lisp image, and monitors any garbage collection activity which occurs. For the most part you can ignore this window, although you may sometimes find the buttons on it useful for breaking into the Lisp process if you run source code which crashes Lisp for any reason. If you wish, you may close the Lisp Monitor window.