NTVDM CPU Has Encountered an Illegal Instruction

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This article was previously published under Q245184

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SYMPTOMS

When you attempt to run a 16-bit program on a computer running Microsoft Windows NT 4.0 Service Pack 3, the program may quit immediately, or you may receive the following error message:

Hidden Console of WOW VDM
The NTVDM CPU has encountered an illegal instruction.
CS: 04c3 IP:3937 OP:c71c 9d 37 00
Choose Close to terminate the application.

When you click Close, you may receive several similar error messages.

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This behavior can occur if you use an incorrect version of the Command.com file. For example, this issue is known to occur if you use a Command.com file included in Microsoft Windows 95, dated 7/11/95.

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RESOLUTION

To resolve this issue, replace the Command.com file in the Winnt\System32 folder with the same file from another computer that is running Windows NT Workstation 4.0 or Windows NT Server 4.0, and then make sure that there are no Command.com files dated 7/11/95 on the computer. You can also replace the Command.com file on the computer with the same file on the Windows NT installation CD-ROM.

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