If you have created and formatted a volume with NTFS or FAT, but you can no longer access files on it, and Disk Administrator displays the volume as Unknown, the Partition Boot Sector for the volume might be bad.
The Partition Boot Sector can be corrupted by viruses. Corruption problems can also occur if you have a dual-boot configuration with Windows 95 and you use the Windows 95 version of Fdisk. To avoid problems with Fdisk, delete the Windows 95 version, make sure that you have the MS-DOS-based version, and run Fdisk only when you start MS-DOS.
To determine if a corrupt Partition Boot Sector is causing the problem, and for the description of the procedures to restore it, see "Replacing the Partition Boot Sector" within Chapter 5, "Preparing for and Performing Recovery."
The permission problem occurs when you have done all the following:
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 on as an administrator and take ownership of all folders, or add the group Everyone back with full control (default).
If there is corruption in the MFT file, there is no general solution. If you suspect this kind of problem, you should contact your technical support personnel for assistance.