Microsoft Windows XP does not start if the following conditions are true:
Windows XP and Windows Vista are installed in a dual-boot configuration.
Windows Vista is installed on the active partition.
The partition on which Windows Vista is installed is subsequently formatted or deleted.
This issue occurs because the startup information is removed when you format or delete the active partition.
To resolve this issue, run the Windows XP installation program from the Windows XP CD to restore the startup information. To do this, follow these steps:
Insert the Windows XP CD into the computer's CD drive, and then start the computer.
When the "Press any key to boot from CD" message appears on the screen, press any key to start the computer from the Windows XP CD.
Note The computer must be configured to start from the CD drive. For more information about how to configure the computer to start from the CD drive, see the computer's documentation, or contact the computer manufacturer.
You receive the following message on the Welcome to Setup wizard page that appears:
This portion of the Setup program prepares Microsoft Windows XP to run on your computer: To setup Windows XP now, press ENTER. To repair a Windows XP installation using Recovery Console, press R. To quit Setup without installing Windows XP, press F3.
Press ENTER to set up Windows XP.
On the Windows XP Licensing Agreement page, press F8 to accept the license agreement.
Select the installation of Windows XP that you want to repair, and then press R.
Follow the instructions to repair Windows XP. After you repair Windows XP, you may have to reactivate your copy of Windows XP.
For more information about a similar issue, click the following article number to view the article in the Microsoft Knowledge Base:
919529 Windows Vista no longer starts after you install an earlier version of the Windows operating system in a dual-boot configuration