msdos error--- need help!

whenever i try to open anything or install anything that requires msdos i get an error message. it says:

 

(its in french so the translation may not be prefect)

Under system (sous-systeme) MS-DOS 16 bits

invite of command - blabla (whatever the command is)

C:\WINDOWS\SYSTEM32\AUTOEXEC.NT. The system file doesn't convene with the execution of the applications of MSDOS or Microsoft Windows. Choose 'Close' to end the application.

 

 

So yeah, I need MSDOS for quit a lot of things and i can barely install anything. If anybody has any idea on what to do then i will be vey gratefull because I have no idea.