Problem when opening setup files

Dear friends,

I get an error message - "C:Windows\system32\autoexec.NT. The system file is not suitable for running MS-DOS and microsoft windows application. Chose 'close' to teminate the application" when i try to instal some of the programs.

Due to which i am facing many problems.

My OS is WINXP with SP1 and NTFC partition.

So please tell me how to solve this problem.

Regards Devrath.N.D