salami brothers. mere dost ka Toshiba laptop hai is me windows 8 instal hai ab ho chahta hai k windows 7 is me install kare leken jab windows ki DVD insert kar ke restart karta hai aur f12 press karta hai us me se DVD ki option par inter karta hai to windows ki installation ke bajahe laptop star hojata hai means windows nai hota is ka Kia masla hai.