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What's a 16bit MS DOS Subsystem?

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.

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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.

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42 comments on “What's a 16bit MS DOS Subsystem?”

  1. Cause:

    This issue may occur if one or more of the following files are missing or damaged:
    Config.nt
    Autoexec.nt
    Command.com

    Resolution:

    To resolve this issue, perform any one of the following three procedures:

    Procedure 1: (Successful and easy to perform)

    Please install a patch from the link given below. When the patch downloads save it on the desktop. Then right click on the downloaded file and choose Extract to and make sure that you choose the directory C:\Windows\System32. If you have got the right directory you will be asked if you wish to overwrite the existing files. Say yes, reboot and try your program again.

    http://homepage.ntlworld.com/spencer.greystrong/XPFiles.zip

    Reply
  2. Yes, im getting something similar to what i see above. My case is only slightly different.

    I have recently installed an ADSL internet connection on my laptop. It worked perfectly fine for the first several days.

    However, now, when i connect the ADSL line everything is fine for a minute or two and then suddenly the connection crashes. This happens for both internet explorer and firefox.

    After the crash occurs, if you go the icon to reconnect to the internet using ADSL, nothing happens. You click on this icon and nothing occurs…zero. Its like it may as well not even be there.
    Also, a couple minutes after the crash, i receive the following pop up message;

    Subsystem MS-DOS 16 bits (this appears in the window pop up header)
    Quote:
    C:\WINDOWS\system32\command.com
    C:\WINDOWS\SYSTEM32\AUTOEXEC.NT. The file of this system is not appropriate to execute MSDOS applications and Windows.
    Choose ‘close’ to finalize the application.

    Then you choose ‘close’ or ignore with the exact same result. The window closes and your are still unable to reconnect to the internet.

    So, my first idea was to reinstall the ADSL internet software. This works…however, the problem just reoccurs and im back to square one.

    So the problem appears to be in this ‘command.com’ MSDOS file in my system32 folder. For some reason it has all of a sudden started to not get along with my ADSL connection.
    What is strange is that it was working fine for several days then it started.

    I have cleaned my laptop for viruses and found several but they have all been eliminated. Same with spyware. All viruses i found seemed to have no connection to this ‘command.com’ file but maybe one caused damage to it somehow.
    Im just not sure.

    Some people have suggested reinstalling windows but id prefer to wait to do this.

    If anyone has any suggestions or experience with this, id love to hear about it.

    Thanks in advance to anyone who responds.

    Reply
  3. This is what appears when i open Jazz Jackrabbit.
    I have downloaded this from the Net. I have Windows XP professional
    .
    16-bit MS-DOS subsystem
    A:\JAZZ.PIF Invalid program file name, please check your pif file. Choose ‘Close’ to terminate this application.
    Perhaps you could help me

    Reply
  4. The patch worked for me. I had this problem also. Upon stumbling to this site using google and reading then downloading the patch. My problem with that 16 bit subsystem disappeared. Thanks. 😀 its been a pain in the A$$ after sooo long. I didnt wanna re-install coz i had lotsa stuff installed.

    Reply
  5. I hope you can help me. Everytime I try to download a game from the internet or i put a very old computer game in it works but when i try to open the file the 16 bit MS-DOS thing comes up and then it says to close or ignor file. Either one does the same thing. Now i can never play all of these games. And i payed money for some of these really old games.
    Please help and please help me fast i cant wait any longer for this 16bit thing.

    Reply
  6. I know that you allready solve this problem but I need you to tell me how to solve it.When I open the game simmilar to one of the questions, I have an error.My windows are xp proffesional.
    16 bit MS-DOS Subsystem
    C:\Sos\Saku_D\SAKU-CD.PIF
    Invalid program file name, please check your pif file.Choose “Close” to terminate the applicaton.
    Please help me I don`t know what to do.

    Reply
  7. Copy the AUTOEXEC.NT file from \WINDOWS\REPAIR to \WINDOWS\SYSTEM32
    If it asks you whether you want to overwrite,
    click yes

    Reply
  8. C:\Sos\Saku_D\SAKU-CD.PIF
    Invalid program file name, please check your pif file.Choose “Close” to terminate the applicaton.
    Please help me I don`t know what to do.

    Reply
  9. —–BEGIN PGP SIGNED MESSAGE—–
    Hash: SHA1

    Depends on what you were doing or when that message comes up.

    Leo
    —–BEGIN PGP SIGNATURE—–
    Version: GnuPG v1.4.6 (MingW32)

    iD8DBQFGADxuCMEe9B/8oqERAtrUAJsFT/DVgTNfy4DZ3+4CDgYsuVf7pgCfevbX
    z6c4NFPCOXE7o/Fc/SaoTDg=
    =pHCT
    —–END PGP SIGNATURE—–

    Reply
  10. 16 bit MS-DOS Subsystem
    Turbo C++ IDE The NTVDM CPU has encountered an illegal instruction. CS:c000 IP:2c40 OP:8f 96 b9 0e ff Choose ‘Close’ to terminate the application…

    Reply
  11. I having same problem with 16 BIT MS DOS. It could be something to do with the command.com, autoexec.nt and config.nt. But i have try it and it doesnt resolved yet. Plz advice!!

    Reply
  12. 16 BIT MS-DOS Subsystem

    C:WINDOWS\SYSTEM32\wuauclt.exe

    The NTVDM CPU has encountered an illegal instruction.

    CS:Odba IP:01a7 OP:f0 41 00 6a 27 Choose ‘Close’ to terminate the application.

    No matter what I do, this box keeps reappearing. It takes my computer a long time to shutdown also.

    Reply
  13. I have an error 16 bit MS-DOS Subsystem
    c:\Windows\system32\wuaudt.exe
    the NTVDM CPU has encountered an illegal instruction. CS:055cIP:01108 OP:of 00 00 00 1a choose close to terminate the application.
    I choose close but the window keep poping up., can you help me fix my problem. thank you

    Reply
  14. I have an error 16 bit MS-DOS Subsystem
    c:\Windows\system32\wuaudt.exe
    the NTVDM CPU has encountered an illegal instruction. CS:055cIP:01108 OP:of 00 00 00 1a choose close to terminate the application.
    Please give solution on my mail id.
    thank you

    Reply
  15. I have an error 16 bit MS-DOS Subsystem
    c:\Windows\system32\wuaudt.exe
    the NTVDM CPU has encountered an illegal instruction. CS:055aIP:0102 OP:63 68 65 6d choose ‘close’ to terminate the application.

    Reply
  16. 16 bit MS-DOS Subsystem
    Turbo C++ IDE The NTVDM CPU has encountered an illegal instruction. CS:c000 IP:03e1 OP:fo 12 02 03 50 Choose ‘Close’ to terminate the application…

    Please help me I don`t know what to do

    Reply
  17. I’m getting a error also.. 16 bit MS-DOS Subsystem…C:\WINDOWS\system32\wuaudt.exe
    The NTVDM CPU has encountered an illegal instruction.
    CS:0551 IP:0108 OP:0f 00 00 00 d0
    Says to choose ‘Close’ to terminate the application. Neither close or ignore seem to work. Hope you can help.

    Reply
  18. 16 bit MS-DOS Subsystem
    Turbo C++ IDE The NTVDM CPU has encountered an illegal instruction. CS:c000 IP:2c40 OP:8f 96 b9 0e ff Choose ‘Close’ to terminate the application

    Reply
  19. 16 bit MS DOS Subsystem
    C:\Users|THECHA~1\AppData\Local\Temp|`tmpa.exe

    This message pops up quite often while doing anything on the computer. Not just at start up. It popped up twice while doing this.

    Reply
  20. 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

    Reply
  21. 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.

    Reply
  22. 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

    Reply
  23. 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 .

    Reply
  24. 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

    Reply
  25. 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

    Reply
  26. 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

    Reply
  27. 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?

    Reply
  28. 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!!

    Reply
  29. 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..

    Reply
  30. 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

    Reply
  31. 16 bit MS-DOS Subsystem
    C:\docume~1\admin~1.del\sUddate.exe
    The NTVDM CPU has encounted an illegal instruction
    CS:0538 IP:0249 Op:65 74 7b 66

    Reply
  32. C:\WINDOWS\_DEFAU~1.PIF

    Invalid program filename, please check your PIF file. Choose ‘Close’ to terminate the application

    Reply
  33. hmm well, am getting this “16 bit MS DOS Subsystem” pop up everytime I start my laptop, but in contrary of the others, when I close it or ignore it, my laptop restart by itself, and now it had worsen as it is restarting every time my desktop loads. This prob started when I’ve last put my pen drive. Isn’t that some kind of virus which has kinda same characteristic with the “16 bit MS DOS Subsystem” ?? What should I do?

    Reply
  34. I get this error message when I try to run an old game.How do i fix the problem to get my game running?I have windows xp home.

    Reply
  35. I have deleted the executable file named “KB 614584” on C:\Users\User\AppData\Roaming\ as it is mentioned on the 16 bit MS-Dos Subsystem Message error.
    …and so i have solved the problem on my friend’s computer. the message has not appeared anymore. 🙂

    Reply

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