The most common cause for this problem involves home directories that were created in iManager on NCP volumes that point to Linux POSIX file systems.
Home directories created in iManager are owned (from a POSIX standpoint) by the Admin user who creates the user object. If a Samba share points to a Linux POSIX file system, then the Samba user must have POSIX access rights to access directory contents. For more information, see Creating Private Home Directories for Samba Users.