Fixing Error 0x000000ED: UNMOUNTABLE_BOOT_VOLUME on Windows XP

The error message 0x000000ED: UNMOUNTABLE_BOOT_VOLUME in Windows XP signifies that Windows cannot access the start-up volume. This issue might stem from various problems such as failing hardware, corrupt files, or a defective hard disk. Follow these steps to tackle the problem:

1. Reboot your computer and attempt to start in Safe Mode. Should you manage to access Safe Mode, perform a virus scan and a disk check to detect and rectify any problems.
2. If accessing Safe Mode fails, consider utilizing the Windows XP Recovery Console. Boot your computer using the Windows XP installation CD, and when prompted, hit R to access the Recovery Console. Here, you can execute commands to mend your system files and boot sector.
3. Should the Recovery Console prove ineffective, a fresh installation of Windows XP might be necessary. This process will delete all your existing data and applications, so ensure you have backups of crucial files before you proceed.
4. If problems persist post-installation, it's likely a hardware issue. Inspect your hard drive for any physical damage or faults, and think about replacing it if required.

Ultimately, regular data backups and system maintenance, including updates and virus scans, are crucial in preventing this error.