Laptop acer aspire 3000

I turn on laptop and this comes up on screen.
Windows could not start because the following file is missing or. Corrupt
\WINDOWS\SYSTEM32\CONFIG\SYSTEM

YOU CAN ATTEMPT TO REPAIR THIS FILE BY STARTING WINDOWS SETUP
USING THE ORIGINALSETUP CD-ROM
SELECT 'R' AT THE FIRST SCREEN TO START REPAIR.

CAN U GUIDE ME THROUGH WHAT TO DO PLZ