NTVDM support files problem

I have had to reinstall my system after a hard drive failure and have been
trying to install a piece of software which I originally had on the system.
Whenever I try to run the setup I get the following error message:

Application popup: 16 bit Windows Subsystem :
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.

I was advised of the following by the software support team:

If you are still receiving the error when installing, please contact your
computer manufacturer or Microsoft. If you would like to look into/correct
this yourself, you can go to Microsoft Support pages and they can give you
articles on how to check and verify that all required NTVDM support files
(DLL) exist on your system. If any of the DLL files are missing or corrupt,
they will also provide directions on replacing these files. Once replaced,
you should have no problems installing our DLM.

I have had a quick look at the support pages at the Microsoft website but
was unable to find what I thought was the actual problem and a solution. If
anyone could advise as to what I should do I would be most grateful.

Regards,

Grant Dunlop