What's wrong with my NJSatr?

Hi, there,

The NJstar communicator 2.2 on my PC (with Windows XP, English version) doesn't although it worked just fine only a few days ago. Everytime when
I click on the NJStar icon, there is an error message "C:\Windows/System32/autoexec.nt. The system file is not suitable for running MS-DOS and Microsoft Windows applications."

Do you know what caused this problem and how to fix it?

Thanks in advance.

Ken222