Hi,
What is the OS on NAS? Are you backing up unix data?
Are you also getting any errors on this directories?
Ensure that NTFS file and directory names are not longer than 255 characters.
.
Refer to the following link for more information.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/naming_a_file.asp
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