16 bit MS-DOS Subsystem NTVDM CPU illegal instruction

When I start up my computer, the 16 bit MS-DOS subsystem pops up with an error message:


The NTVDM CPU has encountered an illegal instruction

CS:0dd8 IP:01c6 OP:63 65 6e 74 65 Choose 'Close' to terminate the application


How do I fix this? I can't seem to figure out if I should delete that .exe or not, as I'm not sure if it's necessary on my computer or simply misplaced. I've scanned my system with McAfee, Norton, PrevX, and AVG and there were no viruses or otherwise found. Any help would be greatly appreciated


Question Info

Last updated April 17, 2019 Views 14,899 Applies to:

Hi kuroryu256,


Since when are you facing this issue?


Possible that a third party program installed on the computer could be causing this issue.


Method 1: Put the computer in clean boot state and check to see if the issue persists; follow the steps mentioned in the article below


How to configure Windows XP to start in a "clean boot" state



Note: Put the computer back to normal startup state, refer the section “Steps to configure Windows to use a normal startup state” in the link


Method 2: You may follow the steps mentioned in the articles below which addresses similar issue


Troubleshooting MS-DOS-based programs in Windows XP



How to Troubleshoot 16-Bit Windows Programs in Windows XP



Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:           

How to back up and restore the registry in Windows


Thanks and Regards:

Ajay K

Microsoft Answers Support Engineer

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