This behavior occurs if the partition marked as active does not contain the Windows boot files or the boot files for another operating system. On Intel-based computers, the system partition must be a primary partition that has been marked as active for startup purposes. This partition must be located on the disk that the computer gains access to at startup. There can be only one active system partition at a time. If you want to use another operating system, you must first mark its system partition as active before restarting the computer.
How to create a bootable floppy disk for an NTFS or FAT partition in Windows XP
If the partition that has been incorrectly marked as active is formatted in the FAT file system, the FAT32 file system, or the NTFS file system, you may be able to use the Windows Recovery Console to correct the behavior.
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NOTE: The system partition refers to the disk volume that contains the files that are needed to start Windows (for example, Ntldr,Boot.ini, and Ntdetect.com). On Intel x86-based computers, the system partition must be a primary partition that is marked active. On Intel x86 computers, this is always drive 0, the drive that the system BIOS searches when the operating system starts.
Using the Recovery Console, copy the Ntldr file from the Windows XP CD-ROM to the root directory of the current active partition. Follow these steps:
Start your computer by using the Windows XP Setup floppy disks or by using the Windows XP CD-ROM.
At the "Welcome to Setup" screen, press F10, or press R to repair.
Press C to start the Recovery Console.
Copy the Ntldr file from the Windows XP CD-ROM to the root of your system partition by using the following commands, pressing ENTER after each command:
Type cd .. to go to the root of drive C.
Note that there is a space between the d and the two periods (..).
Type the letter of the CD-ROM drive.
Type cd i386.
Type Copy ntldr c:.
Type Copy ntdetect.com c:.
Type Bootcfg /add.
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