What the heck are used to be able to save as a DXF And import into my CAD cam software. Now if I import as an AI file it doesn't come in to scale. Seems funny they would get rid of this option even if perhaps it is not optimal for some reason.
Please note that resetting preferences will remove all the custom settings and Illustrator will launch with default settings. You can also take a backup of the folders in case you want to. Location is mentioned in the article.