If Ntldr is damaged or missing, or if the boot sector is corrupted, you can resolve either problem by using the Recovery Console.
To start the computer and use the Recovery Console to replace the boot sector
Insert the Windows XP Professional Setup CD-ROM into the CD-ROM drive.
Restart the computer. If prompted to press a key to start the computer from the CD-ROM, press the appropriate key.
When the text-based part of Setup begins, follow the prompts. Press the R key to repair a Windows XP Professional installation.
If you are repairing a system that has more than one operating system installed, from the Recovery Console choose the Windows XP Professional installation that you need to repair.Note
If you press ENTER without typing a number, the Recovery Console quits and restarts the computer.
The Recovery Console might also show valid installations of Windows NT 4.0. However, the results of attempting to access a Windows NT 4.0 installation can be unpredictable.
When prompted, type the Administrator password. If you do not have the correct password, or if the security database for the installation of Windows XP Professional that you are attempting to access is corrupted, Recovery Console does not allow access to the local disks and you cannot replace the boot sector.
To replace the boot sector, at the Recovery Console command prompt, type: fixboot[drive:]
If you do not specify a drive letter, the Recovery Console replaces the boot sector of the system volume. If you need to replace the boot sector of a volume that is not the system volume, then you must specify the appropriate drive letter.
i have the same problem, but my computer didnt come with a recovery disk!!!!! so i have to boot from the cd drive every time i start the computer lol it gets u into windows but is still a pain in the neck