Certain events can prevent the native Boot Manager of Windows Vista or Windows 7/8.x/10 from running. Some examples are:
- An older version of Windows was installed after a newer version (e.g. Windows XP was installed after Windows 7).
- The boot sector of the Windows partition was corrupted or overwritten somehow.
- Access the Windows RE environment. Instructions for running Windows RE can be found in the article How to Access the Windows Recovery Environment (Windows RE).
- Enter the following command at the Windows RE Command Prompt:
This command will repair the boot sector of the Windows partition.
Note: For more control over the boot sector repair process, see How to Rebuild the Boot Sector for Windows Vista and Windows 7/8.x/10.
- Exit the Command Prompt and restart the computer. This can be done simply by closing the Command Prompt window and then clicking on the Restart button.
- If you then find that the Windows Boot Manager runs but does not correctly boot Windows, you may need to boot back into Windows RE and enter the following command at the Command Prompt:
This command will allow you to rebuild the Windows boot configuration data (BCD).