My standard text editor in the DOS days used to ask me: "There are unsaved changes! Do you want to exit anyway?" Thankful to be warned, I hammered on 'N', No!! When switching to Windows, the standard text editor gave a similar warning: "There are unsaved changes! Do you want to save them before exiting?" From old habit, I hammered on 'N', No!! I didn't keep a log, but I am sure that the total amount of work lost would add up to at least a man-week, maybe two or three, before I had learned my lesson.