If you've ever needed to move large amounts of data across volumes using Windows Explorer, you were probably disappointed to find that you had to recreate all of your permissions.
Links:
[1] http://www.techniquemicro.com/content/copying-permissions-across-volume-boundaries
[2] http://www.techniquemicro.com/tag/ntfs
[3] http://www.techniquemicro.com/tag/regedit
[4] http://www.techniquemicro.com/tag/windows-explorer