Run Windows XP CD
1. Place the Windows installation disc in the CD-ROM and restart your system. Press a key to boot the CD.
2. Press 'Enter' once the welcome screen appears. Review the agreement and scroll to the bottom of the agreement. Press 'F8.'

3. Press 'R' to restore the vital windows components and repair the startup error. Allow the process to finish.
Run the Windows Vista and 7 CD
4. Place the Windows installation CD in the CD-ROM and reboot your computer.
5. Press any key on the keyboard to start Windows from the CD.
6. Choose the language settings and select 'Next.'
7. Choose the system you want to repair and click 'Next.'
8. Click 'Startup Repair' on the 'System Recovery' menu. Allow the tool to repair the startup errors and reboot your system.
Open Windows Advanced Options
9. Reboot your system and press 'F8' in succession, until the 'Windows Advanced Option Menu' appears.
10. Select 'Last Known Good Configuration...' Press 'Enter.'
11. Wait for the system to boot.