Re Issued - 17 NOVEMBER 2005

Subject : "16-bit MS-DOS Subsystem" error message when you run 16-Bit Windows program 

Note : This tech note is applicable to all Users of CAFAM.



When you run CAFAM you encounter the above error. This happens because something, a trojan, virus or some spyware may have attempted to modify a system file called AUTOEXEC.NT located in your operating system folder




Visit the Microsoft website on 


and select the "Knowledge Base" option. Search here for the keywords "16 Bit subsystem" and you will be directed to Microsoft’s Knowledge base detailing the fix.

A direct link to the this item can be found on


Note that from our experience the above equally applies to standalone machines. We have encountered cases where the Network and Server are fine in that the integrity of the files listed have not been compromised, i.e. the firewalls, anti-virus and anti-spyware software in place are working well. The workstation has become compromised on it’s own by some external unauthorised file corrupting the autoexec.nt file. This needs to be corrected as per the details in Microsoft’s website.

Just for the record, we have CAFAM running very well at various sites using:

      - Windows NT Server
      - Windows 2000 Server ) Including Terminal
      - Windows 2003 Server ) Services for remote Login
      - Novell Server - all versions

The workstations are a mixture of

     - Windows98
     - Windows ME
     - Windows 2000
     - Windows XP Professional

None of the above have any problems running CAFAM whatsoever.




Zenner Limited (UK)
Zenner Aviation Inc. (Canada)

UK +44 (0) 1959 565 707
Canada +1 613 384 6523