Direct Disk Access Disabled to Protect Long File Names

• Microsoft Windows NT Workstation version 3.51
• Microsoft Windows NT Server version 3.51
• Microsoft Windows 95

SYMPTOMS

When you install Windows NT 3.51 by running Winnt from a Windows 95 MS-DOS prompt, the following error may occur as Setup is copying files:

   Windows has disabled direct disk access to protect your long file
   names. To overwrite this protection see the LOCK /? command for more
   information.

   The system has been halted. Press CTRL+ALT+DEL to restart your computer.

CAUSE

Direct disk writes using INT 26h or INT 13h fail under Windows 95. This is necessary in a multi-tasking environment to prevent disk corruption from multiple utilities running simultaneously or prevent loss of long file names by applications that are not long file name aware.

The LOCK and UNLOCK commands can be used to work around this protection for DOS utilities (for example, Winnt) if necessary.

Use the following syntax for running LOCK:

   lock <drive_letter>:

   unlock <drive_letter>:

RESOLUTION

To lock a drive to enable direct disk access for Windows NT Setup, do either of the following:

• Boot with the Windows 95 Emergency Startup Disk and at the MS-DOS prompt type:

        lock <drive_letter_to_lock>:
  

  For example:

        lock c:
  

  -or-

• From within Windows 95, select Shutdown from the Start button and choose to Restart the Computer in MS-DOS mode. At the DOS Prompt type:

        lock <drive_letter_to_lock>:
  

  For example:

        lock c:
  

MORE INFORMATION

The error message above is a Windows 95 message and only appears if you start Windows NT Setup by typing Winnt. If you install from the Windows NT compact disc using boot floppies, this error message does not occur because Windows 95 must be running at the time to cause this error.