I had to revert to an old scanner while my scanner is being repaired, so I loaded a Windows 2000 driver in a compatability mode as I did before for this scanner that does not have an XP driver. Soon after, I could not run the CMD.exe file and got a message  "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."
It appears as if my computer thinks it is running windows NT. I removed the scanner driver and related software. No change. I ran system restore four times at various points and failed to restore. otherwise all programs run fine except one that gives me the same message as if it is a DOS based program, YET it is not. Any IDEAS on how to fix this one?From the command prompt type....

copy c:\windows\repair\autoexec.nt c:\windows\system32\

thank you Gary...but the issue is how do I get my command prompt back...can not load cmd.exe or go to DOS mode..If you can't use the cmd box use the GUI and do the copy with Windows Explorer.

Hope this helps.  Thanks Gary. It worked. The program now RUNS and I can start DOS mode if I go to the programs accessories dos prompt, but if I go to start, run,  cmd.exe I get a blank screen that quickly disapears, with no other action. If there is a solution, fine, otherwise I can live without it. MUCH appreciated.http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/ntcmds.mspx