If you receive one of the error messages below when trying to install a DOS based or Windows 16 bit application, it’s likely that one of three essential Windows files has become corrupt or deleted altogether.

16-bit MS-DOS Subsystem

C:\Winnt\System32\config.nt The system file is not suitable for running MS-DOS and Microsoft
Windows applications. Choose ‘Close’ to terminate the application.

16-bit MS-DOS Subsystem

config.nt The system file is not suitable for running MS-DOS and Microsoft Windows applications. Choose ‘Close’ to terminate the application.

16-bit MS-DOS 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.

The files at the root of the problem are shown below.

• Config.nt
• Autoexec.nt
• Command.com

If you’re suffering from the problem, you’ll no doubt be pleased to know that there is a fairly straightforward fix which eliminates the compatibility issue under most circumstances.

• Go to Start, then Run and type “C:\Windows\Repair
• Locate the Autoexec.nt file, right click it and select Copy.
• Go back to Start, then Run, now type %windir%\system32 followed by clicking OK.
• When the System32 folder opens, paste the Autoexec.nt file inside using CTRL and V.

This very quick fix should clear up most issues with 16 bit applications, both DOS based and those that run via Windows.

We should make it clear that this is only a common error on Windows XP systems. It’s unlikely that you will encounter it on the older models, as full support was enabled for 16 bit programs. But as that technology becomes slowly out of date, you can expect to see a few more problems arising.

So how do the core files become corrupt? Well, it could be through an accidental deletion from an inexperienced user, or it could be the result of a more damaging incident – such as the spreading of a virus or a worm.

Many viruses, particularly the more damaging breed, will attack the System32 folder as it holds some files which are critical to the functionality of a system. Unfortunately that can mean an easy corruption of the aforementioned files that we’ve discussed, particularly autoexec.nt.

Be sure to equip your system with the latest anti-Virus software and this will act as a good barrier between your critical files, and the grasp of a malicious hacker. Viruses aren’t the only reason behind file corruptions, of course. Spyware and malware can mess with the integrity of your files by writing files messily to the hard drive.

It’s a good idea to run regular system scans to weed out the corrupted files and to draw attention to any bad directories. Thankfully, the Windows Repair utility makes it quite easy to deal with 16 bit errors. If you’re running applications in a 16-bit environment and receiving the errors at the top of the page, you should check your core files before running a full virus scan. The error itself may sound somewhat optional, but it will always result in the program being terminated – whether you choose to close it or not.