Unmountable boot volume in Windows XP.

Question

Corrupt boot.ini file

To resolve this issue you will need to boot into the recovery console.
In the recovery console type chkdsk /p to check to see if the disk drive is bad or marked as dirty. See the chkdsk command page for further information and help with this command. If errors are located during the check skip to the next section.
If after performing this check it is unable to locating anything wrong with the hard disk drive, reboot the computer.
If after performing this step the computer still has the same issue, reboot the computer and load back into the recovery console.
Once back into the recovery console type chkdsk /r to locate any bad sectors and recover any data. If errors are located during the check skip to the next section.
Once completed reboot the computer to determine if this has resolve your issue.

Note: If after running either of these chkdsk commands your computer is able to successfully boot into Microsoft Windows XP make sure you have all the latest updates for your computer.

Seriously corrupted or bad hard disk drive

If while running the above steps you encounter errors with the hard disk drive or the above steps do not resolve your issue it is likely your hard disk drive is failing or has already failed. To determine if this is the case it is recommended you run the Windows XP setup, delete all partitions, recreate the partitions, format the hard disk drive, and reinstall Windows XP.

If errors are encountered during the creation of the partitions or the format process the hard disk drive is bad and should be replaced.