Error: 16-bit MS-DOS Subsystem.
C:\WINDOWS\system32\AUTOEXEC.NT

An error message similar to the following appears when trying to install or run the program:

  • “C:\WINDOWS\system32\AUTOEXEC.NT. The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose ‘Close’ to terminate the application.”

Explanation

The AUTOEXEC.NT file may be missing or may have been corrupted, due to a variety of reasons.

One common cause of this error is during the installation of Windows XP Service Pack 2, which may delete the AUTOEXEC.NT file. As a result, when trying to run certain applications which make use of 16-bit technology an error message like the one above may be displayed. The error message can be misleading, because it is displayed even if the AUTOEXEC.NT file is not actually missing.

This error may also be the result of corruption of the AUTOEXEC.NT file, in which case the following procedure may be helpful in restoring a valid file. If the corruption is due to hardware failure, try de-fragmenting your hard drive and/or scanning it for errors.

The “AUTOEXEC.NT” file being deleted has also been related to virus programs. You may want to virus-check your system.

Possible Solution

To verify whether you have the file, open a new Explorer window and type %windir%/system32/ in the address bar. If AUTOEXEC.NT is not listed:

  1. Browse to %windir%/repair/ (this is usually C:\WINDOWS\repair).
  2. Copy the AUTOEXEC.NT file, and browse to %windir%/system32/ (usually C:WINDOWS\System32).
  3. Paste the copy of AUTOEXEC.NT.

Similar error messages include:

  • “C:\Winnt\System32\config.nt The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose ‘Close’ to terminate the application.”