Are you dual-booting ?
If you only have Vista and you're getting messages about NTLDR (the XP boot loader), then most likely you're booting from the wrong device, possibly a second HDD which had XP on it in the past.
Check your BIOS HDD boot sequence to make sure you're booting from the correct HDD, and disconnect/reconnect the HDD cables a few times to clean the contacts. That can sometimes cause the "real" OS to disappear and the BIOS will try to boot the next available device.