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Microsoft KB Archive/138923

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Knowledge Base

Partitions Displaying as Unknown in Disk Administrator

Article ID: 138923

Article Last Modified on 11/1/2006


  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 3.5
  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition

This article was previously published under Q138923


Disk Administrator displays an NTFS partition as unknown if the permissions on the root of the partition are changed. When you attempt to access the partition through File Manager, you receive the following error message:

You do not have permissions to access directory.

If you try to access the drive from a command prompt, you receive the following error message:

Access denied.


This occurs when a second partition or volume set is created and the group, "Everyone" is removed from the Access Control List(ACL) and then a specific user is granted access. The single user has normal access, but when other users log on or if Windows NT is reinstalled, Disk Administrator sees the drive as unknown.


To correct this problem, log in as an administrator and take ownership of all directories or add the group Everyone back with full control (default).

Additional query words: prodnt

Keywords: kbhowto kbother KB138923