Boot Sector Repair

Ask when you did a reformat. When everything works well does not work, check your warranty, otherwise you can buy brand new hard drive.

If you have an XP installation disk try.

To replace damaged ntldr and ntdetect.com you can copy fresh files from the XP CD using the COPY command. Boot with the XP CD and enter the Recovery Console (boot into the XP installation disc and wait for the main selection screen to show, then press "R" to enter the Recovery Console). At the prompt type the following commands (where "X" is the letter of your CD-ROM) for the files to replace the old files
COPY X: \ i386 \ NTLDR C:
COPY X: \ i386 \ NTDETECT.COM C:

To repair a damaged boot sector FIXBOOT type the command and press Enter. Then answer "Y"

See if it works.