Err Msg: The Following File Is Missing or Corrupt...


When you start your computer, you may receive the following error message:
The following file is missing or corrupt: COMMAND.COM. Type the name of the Command Interpreter.


This problem can occur if you install Windows 98 or Windows Millennium Edition (Me) in a dual-boot environment with MS-DOS, install Windows again, and then uninstall Windows. The Master Boot Record (MBR) may not be properly updated after you uninstall Windows. The MBR loads the Jo.sys file instead of the Io.sys file from the root folder of drive C. The Jo.sys file can not load the MS-DOS versions of the Msdos.sys file and the file that are restored after you uninstall Windows 98.


To resolve this problem, use the MS-DOS 6.x Upgrade Setup Disk 1 to restart your computer, and then use the SYS command on drive C. To do so, follow these steps:

  1. Place the MS-DOS 6.x Upgrade Setup Disk 1 in drive A, and then restart your computer.
  2. Press the F3 key when MS-DOS Setup starts to exit MS-DOS Setup.
  3. Type sys c:, and then press ENTER.
  4. Restart your computer.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

More Information

The Jo.sys file is used by Windows 98 and Windows Me in a dual-boot environment with MS-DOS.

For additional information about how to use the Startup menu in Windows 98, click the article number below to view the article in the Microsoft Knowledge Base:

178548 No 'Starting Windows 98' Message at Startup