Error message

I get this when I try to run any program that needs ms-dos to work… I use windows xp, and have looked at some sites to get it to work, but no luck so far…

16-bit MS-DOS Subsystem
path to the program that you are trying to start or install
C:\Windows\System32\Autoexec.nt The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose ‘Close’ to terminate the application.