I have an error message coming up on my computer after trying to
reinstall several games.  (our computer crashed and was refurbished,
still has Windows XP, Professional).  They are not old games, and
worked on our system before.  The error message
states-C:\WINDOWS\SYSTEM32\Autoexec.NT.The system file is not suitable
for running MS-DOS and Microsoft Windows applications.  It then has a
click on close or ignore.  Sometimes when you ignore it works, most of
the time it doesn't.  Help!!!

Hi,
Thanks for your question.

Your computer's problem is an issue with one OR more of your operating
system files either being missing or corrupted. Most likely (but not
restricted to) one
of the following Window's operating system files:
- Config.nt 
- Autoexec.nt 
- Command.com 

This is a not a rare problem when trying to run MS-DOS or 16-bit
Windows-based programs (that almost always pre-date Win NT/XP
opertaing systems).

The solution to your problem can be found at Microsoft's website:
http://support.microsoft.com/default.aspx?scid=324767
You will need your original Windows XP CD.

1. Insert the CD into the CD drive or DVD drive. 
2. Click Start, and then click Run. 
3. In the Open box, type cmd, and then click OK. 
4. At the command prompt, type the following commands, pressing ENTER
after each command:


expand CD-ROM Drive Letter:\i386\config.nt_ c:\windows\system32\config.nt 
expand CD-ROM Drive Letter:\i386\autoexec.nt_ c:\windows\system32\autoexec.nt 
expand CD-ROM Drive Letter:\i386\command.co_ c:\windows\system32\command.com
exit  
5. Start or install the program. If the issue is resolved, do not
complete the remaining steps. If the issue is not resolved, go to the
next step.
6. Note: The Command.com file is not edited or created in this in the
following process. Because of this, you may have to expand it from
your Windows XP CD-ROM.

Start Notepad. 
7. In Notepad, type the following entries:    dos=high, umb
device=%SYSTEMROOT%\system32\himem.sys
files=40
 
8. On the File menu, click Save As. 
9. In the File Name box, type Config.nt, and then click Save. Close
the Config.nt file.
10. On the File menu, click New. 
11. In the new blank document, type the following entries: @echo off
    lh %SYSTEMROOT%\system32\mscdexnt.exe
    lh %SYSTEMROOT%\system32\redir
    lh %SYSTEMROOT%\system32\dosx
    SET BLASTER=A220 I5 D1 P330 T3
 
12. On the File menu, click Save As. 
13. In the File Name box, type Autoexec.nt, and then click Save. Close
the Autoexec.nt file.
14. Start Windows Explorer. Locate the Config.nt file, right-click the
Config.nt file, and then click Copy.
15. Right-click the %SYSTEMROOT%\System32 folder, and then click Paste. 
16. Locate the Autoexec.nt file, right-click the Autoexec.nt file, and
then click Copy.
17. Right-click the %SYSTEMROOT%\System32 folder, and then click Paste. 
18. Locate the Command.com file, right-click the expanded Command.com
file, and then click Copy.
19. Right-click the %SYSTEMROOT%\System32 folder, and then click
Paste. Restart your computer.
If the issue continues to occur, copy the Autoexec.nt and Config.nt
files from the Repair folder in Windows to the System folder. To do
so, follow these steps: 1. Click Start, click Run, type
c:\windows\repair, and then click OK.
2. Right-click autoexec.nt, and then click Copy.  
3. Click Start, click Run, type c:\windows\system32, and then click OK. 
4. Right-click anywhere in that folder, and then click Paste. 
5. Right-click the Autoexect.nt file that you just copied, and then
click Properties.
6. Click to select Read-Only, and then click OK.  
7. Repeat steps 1 through 6 to copy the Config.nt file. 
Note You must enable Read-Only permissions or the files will be
removed after you restart Windows

Further related links:
http://support.microsoft.com/kb/314106/
http://support.microsoft.com/kb/314106/
Please let me know if this was helpful.