" The Collection had been created/modified by an HP Engineer (adding a wildcard) and the engineer had inadvertently altered the Collection so that it was very similar in form and function to the “All Systems” Collection. The Task Sequence contained automation to – here it comes – format the disks. Yes, the disks of some 9,000 PCs and 490 servers (including domain controllers) were formatted and wiped clean."
Read more http://myitforum.com/myitforumwp/2012/08/06/sccm-task-sequence-blew-up-australias-commbank/