installing printer software Lexmark X85

> I am running Windows XP Professional, when tring to
> install the discs i keep getting an error message, the
> error box title is:
> 16 bit windows Subsystem
> the message reads:
> C:\windows\system32\autoexec.NT
> the system file is not suitable for running MS-DOS and
> microsoft windows application
> Choose close to terminate the application.
> The other option box is to ignore but whichever option is
> chosen the application hangs as if it is still trying to
> load, the only way to stop it is to re-boot
> Please could you let me know how to get over this problem.
> thanks in advance,
> Dave