I suspect the the file system on the NAS is FAT32. If you change it to NTFS it should correct the problem.
You have a utility called CONVERT that will change the file system. For example, CONVERT E: /FS:NTFS /V
Bruce
Here's the help screen:
C:\>convert /?
Converts a FAT volume to NTFS.
CONVERT volume /FS:NTFS [/V] [/CvtArea:filename] [/NoSecurity] [/X]
volume Specifies the drive letter (followed by a colon),
mount point, or volume name.
/FS:NTFS Specifies that the volume will be converted to NTFS.
/V Specifies that Convert will be run in verbose mode.
/CvtArea:filename
Specifies a contiguous file in the root directory
that will be the place holder for NTFS system files.
/NoSecurity Specifies that the security settings on the converted
files and directories allow access by all users.
/X Forces the volume to dismount first if necessary.
All open handles to the volume will not be valid.