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Article ID: 156687 - Last Review: February 20, 2007 - Revision: 2.1

This article was previously published under Q156687


When you start a 16-bit application, you receive an error message similar to the following:
16 Bit Windows Subsystem - Hidden Console of WOWVDM.
The NTVDM CPU has encountered an illegal instruction. Source


When you receive WOWVDM error messages when starting 16 bit applications, they may be caused by problems with the Config.nt or Autoexec.nt file. These files are parsed each time a VDM is started. If there are problems with these files, you may see error messages such as the above.


Either restore the Config.nt or Autoexec.nt file, or remark (REM) any nonstandard lines in the existing files to determine which file is the source of the errors. Remove the offending lines.


Also, check the versions of the files. The modified date should be the same as the dates of the original installation of Windows.

Rename any versions of that are not of these dates, with the exception of a version of in the root folder of the boot partition (usually drive C) and the Windows folder if you are dual-booting with Windows 95 or Windows 98.

You should also make sure that there is only one copy of the Windows file, in the System32 folder.

  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Windows 2000 Datacenter Server
  • Microsoft Windows NT Workstation 3.5
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 3.5
  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition
kbprb kbusage KB156687
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