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C:\WINDOWS32\SYSTEM32\AUTOEXEC.NT. The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose 'Close' to terminate the application.

What is this? Some of my programs, that used to work on my XP machine, no longer work. How do I repair this?

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This symptom usually means Windows' legacy DOS/16‑bit support is either missing, damaged, or simply not available on the edition you are running. As pointed to the official guidance and offered a compatibility tweak that helps some apps, the next steps are to identify whether the problem is environmental (OS edition, recent cleanup/antivirus, corrupted system files) or the application itself (real DOS vs. 32‑bit Windows).

Quick diagnostic checklist:

  • Confirm whether the installed Windows is 32‑bit or 64‑bit (64‑bit releases do not provide the legacy DOS subsystem).
  • Determine whether the failing programs are true DOS or 16‑bit Windows apps rather than modern 32‑bit software.
  • Note any recent system changes (service packs, AV scans, repair tools) that might have removed or corrupted legacy support files.

Repair and workaround options:

  • If the OS is 64‑bit, run the older apps inside a virtual machine (recommended) or use an emulator. For DOS-only titles, try DOSBox; for 16‑bit Windows software, use a 32‑bit VM running Windows XP/2000.
  • If the OS is 32‑bit, repair the missing or damaged DOS support by using Windows repair tools or restoring the original system support files from trusted installation media or a known-good system; avoid downloading individual system files from random sites.
  • If a virtual approach is chosen, VirtualBox is a free option for creating a 32‑bit guest, and DOSBox works well for pure DOS apps: VirtualBox DOSBox.

Final notes:
Document changes and back up any system files before replacing them. The Microsoft documentation on the legacy DOS subsystem explains the limitations and why some fixes only apply to 32‑bit Windows; consult it when choosing repair versus virtualization: .

Recommended Answers

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Member Avatar for Laser

The 'CD' in step #1 is Windows XP not the program you're having trouble with.

C:\WINDOWS32\SYSTEM32\AUTOEXEC.NT. The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose 'Close' to terminate the application.

What is this? Some of my programs, that used to work on my XP machine, no longer work. How do I repair this?

Member Avatar for tayspen

Not sure how much this will help,but you can right click on a program and hit properties. Them the compatibility tab, and select an older OS.

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