I just got my copy of “How to Break Software” yesterday. I read through the first half today and already caught a couple of issues in the DrRacket IDE. Choose File -> Search in Files and then clear the directory name input and click OK. Some exception window shows up. Next, try setting the font size by dragging the slider in preferences all the way to the left. The program hangs instantly, and the erroneous setting is stored for the next startup. The only way to recover is to manually edit the config file in %appdata%/Racket to save the day.