1. Place the Windows 7 installation disk into the optical disk drive. Restart your computer.
2. Follow prompts to press any key when the 'Press any key to boot from CD or DVD' window appears. Wait for Windows to load the files.

3. Follow prompts to select your language, time and keyboard or input method at the 'Install Windows' screen. Click 'Next.'
4. Click 'Repair your computer' at the bottom of the next screen.
5. Click the radio button next to 'Use recovery tools that can help fix problems starting Windows' option and select your operating system. Click 'Next.'
6. Click 'Startup Repair' at the 'System Recovery Options' screen. The tool will automatically detect and fix startup errors. Your PC might restart more than once.