UNMOUNTABLE_BOOT_VOLUME After installing or upgrading Windows XP from Windows 95 or 98 an error message:
STOP 0x000000ED (0x aaaaaaaa ,0x bbbbbbbb ,0x cccccccc ,0x dddddddd ) UNMOUNTABLE_BOOT_VOLUME appears when Windows tries to load.

This error is generated by design through Microsoft to prevent any data loss during operation. By design this error can incur when:

  • A 40-wire cable is used to connect an Ultra ATA hard drive to an Ultra ATA hard disk controller.
  • Improper BIOS settings
  • A file system may be damaged and cannot be mounted.

To resolve this issue:

  1. Replace the 40-wire cable with an 80-wire Ultra ATA Cable
  2. In the BIOS load the “Fail Safe Default Settings”.
  3. Restart the computer. If it doesn’t correct the problem a file system may be damaged.

Repairing a Damaged File System

  1. Restart the computer with the XP install disk.
  2. Press R to select the Repair Option at the “Welcome to Setup” screen.
  3. Enter administrator password if prompted to do so.
  4. At the next prompt press 1 and Enter .
  5. This should bring you to the command prompt “C:\” or “C:\Windows”.
  6. Type chkdsk /r and press enter. This will scan the disk and repair any errors.
  7. Type fixboot X: where “X” is the drive that you are installing the operating system on.
  8. Restart the system. If Windows still errors repeat steps 1 thru 5.
  9. Type fixmbr at the command prompt.

If all the above steps fail you may run a low-level format on the drive using SeaTools. Run the Write Disk Pack. This process may take several hours depending on the size of the drive.