Your question is off-topic for this newsgroup, but see
http://support.microsoft.com/?kbid=324767 "Error message when you
install or start an MS-DOS or 16-bit Windows-based program".
WodTalker wrote:
> I have used Microsoft Bookshelf 2000 CD for years and suddenly it won't load.
> An error message comes up labelled "16 bit Windows Subsystem:
> WINDOWS\SYSTEN32\AUTOEXEC.NT -- System file not suitable for running MS-DOS
> and Microsoft Windows applications. Choose 'Close' to tetminate the
> application." Then two buttons with close or ignore. Click either and the
> program won't run.
>
> Is there any way to get around this?
>
>