Command.com is the command interpreter for 16-bit programs. If you open a Command.com session and type a DOS command, like DIR, and press Enter, nothing happens?
Command.com is dependent on the 32-bit command interpreter, CMD.EXE, for many of it's functions. If Command.com can NOT locate CMD.EXE, it will exhibit the above behavior.
Command.com uses the ComSpec environment variable to locate CMD.EXE. ComSpec must contain the full path to CMD.EXE.
To resolve this issue:
1. Use Notepad to edit %SYSTEMROOT%\SYSTEM32\AUTOEXEC.NT.
2. If a ComSpec= line exists, remove it and save the updated AUTOEXEC.NT file.
3. Use Control Panel / System / Advanced / Environment Variables to update the ComSpec environment variable. Select the ComSpec line and press Edit.
4. Type the full path to CMD.EXE. The default location is %SystemRoot%\system32\cmd.exe.
5. Press OK until Control Panel is closed.