The document discusses how testers will not break a system but users who do not understand how to properly use a system may cause issues. Specifically, it notes that while testers will not think to use a CDROM drive as a drinks holder, an actual user just might, potentially damaging the system.

1. www.project-management-podcast.com
The testers won't break the system
but the user who thinks the CDROM drive is a drinks holder will.