Mere pass toshiba satelite c850 note book hai.us main windows 8 instaled hai.main us main windows 7 install karna chahta hun.lekin jab main is main window 7 ki cd dalta hun.to jab main computer korestart karta hun to boot frm cd ka option nahien aata f12 bhi press kar ke check kar chuka hn lekin.koi faida nahien hua.please koi mujhe bata sakta hai ke boot from cd ka optionkese laaon.