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What's a 16bit MS DOS Subsystem?

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Summary: There are a couple things to check when a 16 bit MS DOS Subsystem error pops up on your machine.

I get this msg when i start up my computer.

16 bit MS DOS Subsystem
C:\WINDOWS\system32\Debug.exe
C:\WINDOWS\SYSTEM32\SUTOEXEC.NT.
The system is not suitable for running MS-DOS and Microsoft Windows applications. Choose 'Close' to terminate the application. I did not have this before. Please advise me how to fix this problem.

While there are a couple of clues in that error message, the results are inconclusive.

The 16 bit subsystem is what allows some older MS-DOS software to run in today's Windows NT and XP. It sets up a simulated MS-DOS environment, and many old applications can run fairly well. (This not to be confused with the Command Shell, which is a true 32 bit Windows application.)

But in this case it looks like some old 16 bit MS-DOS application is attempting to start when you log in. In fact, it's possible that the 16 bit debugging program debug.exe is being started.

If you had just installed some new software, I might suspect that as the cause. Especially if it was a new install of some old software package. However my assumption is that this isn't the case.

So I would do three things:

  • scan for spyware

  • scan for viruses

  • check out what's starting when you boot windows

I actually suspect spyware, but I've not seen one that starts a 16bit program before. In any case, since it's trying to start when you start up Windows, the last approach should allow you to disable it if the spyware and virus scan don't stop it.

Related:

Article C2218 - November 9, 2004

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Recent Comments
36 Comments

16 bit MS-DOS Subsystem
Turbo C++ IDE The NTVDM CPU has encountered an illegal instruction. CS: 0060 IP: 0075 OP: f000fo 3705 Choose 'Close' to terminate the application

Posted by: pankaj at February 28, 2009 8:24 AM

I click on a .DO1 file and receive a 16 bit ms-dos
subsystem message: C:\DOCUME~1\owner\MYDOC~1\
SHORTC~1.PIF Close to terminate.
Any help appreciated.

Posted by: Arthur Robinson at March 4, 2009 10:01 AM

16 bit MS-DOS Subsystem
C:\windows\system32\2.exe
The NTVDM CPU has encounted an illegal instruction
CS:0da4 IP:0112 Op:62 c2 c0 45 bd 41

Posted by: Dalton at March 5, 2009 2:38 PM

16 bit MS-DOS Subsystem
C:\windows\system32\mdm32.exe
The NTVDM CPU has encounted an illegal instruction
CS:0545 IP:0261 Op:64 63 2E 79 76

Also try to run apps -like run-open-___ ok a black box pop up on top c:\windows\system32mdm32.exe rest of box M T .

Posted by: Dan at April 5, 2009 11:43 AM

dear sir,
the prince game is not run in my pc error given
16 BIT MS-DOS Subsysteam
the NTVDM CPU has encountered an illegal instruction
CS:c000 IP:019e OP:63 70 36 31 2d
my pc windows xp sp2

Posted by: kamlesh patel at April 11, 2009 9:47 PM

sir
I can't start my MS-DOS application.error comes invalid directory pif file is missing. i am using windows xp.what should i do

Posted by: mee at April 23, 2009 5:04 AM

i want to open websites/FTP by using CMD line, how do that, i have trying by giving the particular webpage name and try to open in the CMD Line, but it gives an error C:\WIndows\system\cmd.exe - sa
The NTVDM CPU has encountered an illegal instruction
CS:0557 IP:0110 OP:65 6f 2e Choose 'clos' to terminate the application

Posted by: Satish at May 2, 2009 1:03 AM

Sir,
My machine gives an "16 BIT MS-DOS Subsysteam error, "the NTVDM CPU has encountered an illegal instruction"
CS:053f IP:0206 OP:63 61 74 69 6f
my p has windows xp. With several scans no successs, what shall i do?

Posted by: Roosevalt Faraja at May 7, 2009 6:41 AM

hi i have a HP laptop with windows XP home edition. i have recently been experiencing 16bit MS DOS error mesages that go as follows: 16bit MS DOS Subsystem C:/DOCUME~1\user\dsccds.exe The NTVDM CPU has encountered an illegal instruction. CS: 0dd2 IP: 0206 OP: 63 61 74 69 6f Choose 'close' to terminate the application.
The error message usually pops up after several blank, black windows have popped up upon start/restart or just after general sleep mode. in fact, the screen is popping up regularly as i type this message and goes away. i have norton anitvirus and a full system scan revealed nothing but a tracking cookie. is my particular message a result of a virus or a program application problem like the comments in this article??
how do i fix this? should i take my laptop to professionals?
thank you in advance for speedy help!!

Posted by: sam at May 10, 2009 3:33 AM

C:\Windows\system32\mshrm.exe
The NTVDM CPU was encountered an illegal instruction
CS:0541 IP:027a OP:63 75 6d 65 6e
Choose 'Close' to terminate the program..

when i choose close nothings happen
but when i choose ignore this will be the appear

C:\Windows\system32\mshrm.exe
The NTVDM CPU was encountered an illegal instruction
CS:0541 IP:0376 OP:63 75 6d 65 6e

please help my probs..
give somthing like instruction or files that may help my problem

ill try
16-Bit MS-DOS subsystem quick fix error
and I also try
Free Restore
when i run it
the MS-DOS will appear again
like in the TOP..

Posted by: mishaelramos at June 19, 2009 7:27 AM

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