Err: Win16 Subsystem Unable to Enter Protected Mode

The information in this article applies to:

• Microsoft Windows NT Workstation versions 3.5 and 3.51
• Microsoft Windows NT Server versions 3.5 and 3.51

SYMPTOMS

When you attempt to access a 16-bit application from Windows NT and are using Fprot.exe, the following error message is displayed:

   The Win16 Subsystem was unable to enter Protected Mode,
   DOSX.EXE must be in your AUTOEXEC.NT and present in your PATH.

CAUSE

Fprot.exe inadvertently changes the file's attributes to read/hidden/system attributes. The following may be affected:

• WINNTxx
• WINNTxx\SYSTEM
• WINNTxx\SYSTEM32
• WINNTxx\SYSTEM32\DRIVERS
• WINNTxx\SYSTEM32\REPAIR

RESOLUTION

Compare the damaged system with a fresh install of NT on a second computer and reset the attributes with either the "attrib" command or File Manager.

MORE INFORMATION

ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [[drive:] [path] filename] [/S]

  +   Sets an attribute.
  -   Clears an attribute.
  R   Read-only file attribute.
  A   Archive file attribute.
  S   System file attribute.
  H   Hidden file attribute.
  /S  Processes files in all directories in the specified path.