What should I do if XP fails to start after upgrading to Vista?

When you try to boot after failing to upgrade to Windows Vista, but you can't enter Windows XP system, you can't enter Vista, but a black screen and a blinking bottom line. How to solve this problem when you have this problem? Take a look at the following steps: 1. Start your computer with the windows xp CD. 2. On the "Welcome to the installer" screen, press R to repair Windows. 3. Log in to the windows xp installation you want to repair. 4. Type fixboot and press Enter. 5. Type y and press Enter to confirm that you want to write a new boot sector to the system partition. When you do this, the following message is displayed: A new boot sector was successfully written. 6. Type exit and press Enter to exit the recovery console. 7. Restart your computer and complete the Windows Vista upgrade.