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Legacy Update Help

Fix “NTLDR is missing” after installing updates

The final version of the Windows Update Agent released for Windows XP, version 7.6.7600.256, has a bug that triggers a limitation of XP’s bootloader (NTLDR). This seems to only occur on Windows XP Home Edition and Embedded, and is not an issue on Professional.

The bug is that the installer enters an infinite loop of creating temporary folders in the root of C:, which causes the NTFS Master File Table (MFT) to become too fragmented for NTLDR’s master boot record (MBR) program to make sense of. This is covered by KB320397, a patch for XP Service Pack 1 that was later built into SP2, but the issue still seems to occur despite the fix. Legacy Update 1.6 and later work around this by using an older version of the Windows Update Agent without this bug. If you’ve installed an older version of Legacy Update, or manually installed Windows Update Agent 7.6.7600.256, you can resolve this in one of a few ways:

  • If you have a bootable third-party defrag tool, it may be able to defragment the MFT. If it provides this option, you should be able to boot into Windows again once it has done this. Note that the Windows built-in defrag tool doesn’t support defragmenting the MFT.

  • If your PC has a floppy drive, and you have a spare floppy and another PC with a floppy drive, you can use the Microsoft bcupdate2.exe utility.

    1. Download bcupdate2.exe, and copy it to a bootable MS-DOS floppy.

    2. If you need to make an MS-DOS floppy, you can right-click A: → Format → check the “Create an MS-DOS startup disk” box, or use Bootdisk.com’s MS-DOS 6.22 floppy.

    3. At the MS-DOS prompt, type bcupdate2 C: and press Enter (assuming your Windows installation is on drive C:).

    4. Once you return to the A:\> prompt, remove the floppy and press Ctrl-Alt-Delete to restart.

  • If you have a dual-boot, or bootable Windows PE CD/USB such as Hiren’s Boot CD, you can repair this without additional tools.

    1. Browse to your C: drive, then sort by Date Modified.

    2. Click the first folder with a long, random name, then scroll to the last folder, hold Shift, and click that. Make extra sure you have only selected folders named with a long, random hash, which will look something like “8a3df9adb37cd66105f9c2”.

    3. Cut (Ctrl-X) the selection, then find somewhere else you can put them (perhaps make a folder on your desktop in C:\Documents and Settings\MyName\Desktop), and paste (Ctrl-V).

    4. Open a Command Prompt (likely from the Start menu), and run chkdsk C: /r. This will perform a full repair, which can take a long time.

    5. Once the repair has completed, restart your computer.