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Microsoft KB Archive/169171

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Knowledge Base

Article ID: 169171

Article Last Modified on 11/1/2006


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

This article was previously published under Q169171


Certain 16-bit programs may stop responding (hang) or not run. When you look at Processes in Task Manager, it shows NTVDM at or around 100 percent CPU time.


This problem occurs when the PATH statement is approximately 200 characters or more in length.

This problem has also been seen when security on the files in the %SystemRoot%\System32 folder has been made too restrictive. Specifically, the users running 16-bit programs must have at least Read (RX) access to all files in the folder and all subfolders. This is the configuration by default.


Use one of the following methods to resolve this problem:

Method 1

The PATH statement can be found in two locations. Shortening one or both statements should fix the problem.

PATH in System Properties:

  1. In Control Panel, double-click the System icon. Click the Environment tab.
  2. Under System Variables, select PATH and shorten the value.
  3. Click Set, and then click OK.

PATH in Autoexec.nt:

  1. Use Notepad to open Autoexec.nt, which is located in the %SystemRoot%\System32\Autoexec.nt directory.
  2. Shorten any PATH= statement.
  3. Save Autoexec.nt.

The NTVDM must be terminated before the new PATH will be used. To terminate the NTVDM process, go to task manager and select NTVDM. Click End Process.

Method 2

Increase the environment size in Config.nt:

  1. Use Notepad to open Config.nt, which is located in the %SystemRoot%\System32 directory.
  2. Add the following statement:

          SHELL=%systemroot%\system32\ /e:2048

This will increase the environment size to allow the path statement to remain at the current length. If problems persist, increase the e: parameter.


Microsoft has confirmed this to be a problem in Windows NT version 4.0.

Additional query words: slow DOS hang VDM

Keywords: kbbug kbpending KB169171