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Repair Installation of Windows XP or Windows 2000

Last reviewed: January 2009

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A Repair Installation of Windows 2K/XP and an "in-place upgrade" have similar results.
The information here applies to all Windows 2K/XP users and not just those who are dual-booted.

Re-installing Windows over an existing installation copies original system files to the hard drive but also resets certain settings to default values. It will feel like a new installation - and will appear to take longer! Also, you will receive a few prompts so it cannot be left unattended. However, the end result is the correct (expected) allocation of drive letters and a fully functional Windows. Installed 2K/XP software should be fully functional; most settings, passwords, saved items, etc., should be unchanged.

A Repair does carry some small risk of failure and should only be undertaken when other methods have been tried and failed. All users should first read Repair a Dual-Boot even if not dual-booted in case your problem is with the boot sector and the boot files.

The Repair makes certain changes that may upset some users. The changes given below apply to 2K but you can expect the same from XP. Please note item 5 below in Preparing ... re Internet Explorer 7.

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Items Changed:

1. Drive letters are changed to accurately reflect the current drive and partitions.
2. Installed Service Packs, hotfixes, IE upgrades are rolled back to original installation state, and will need reinstallation.
3. All existing restore points are removed and a new system checkpoint restore point is created.
4. Default registry values are restored.
5. Default permissions are reapplied.
6. COM and WFP are re-registered.
7. Plug and Play devices, and the HAL, are re-enumerated.
8. Device drivers not integrated into Windows may need reinstallation.
9. Automatic Updates (XP) will cease functioning until you manually download/install critical updates yourself.

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Items Not Changed:

1. Installed components and programs are unaffected and will continue to function normally.
2. Passwords are unaffected.
3. Third-party registry entries are unaffected.
4. The computer's role is unaffected.

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Preparing for a Repair Installation:

1. Installation CD: You need a full Windows XP installation CD. You can use an OEM XP Pro or Home, retail XP Home or Pro full or upgrade version CD of the same version to perform a Repair Installation. However, OEM Restore disks or hidden restore folders on the hard drive will not work for the Repair Installation. The CD must be capable of executing a non-destructive install - some OEMs do not!
2. Key Code: You may need your XP/2K 25 character product Key Code (or retrieved it from the hard disk using the free Produkey utility, 43 KB).
3. Free Space: You may need plenty of free hard disk space to accommodate a large swap file.
4. NTLDR and A Reinstall is not possible if the hidden files NTLDR and are not on the system partition (C:). If necessary, use these command from the Recovery Console run from the XP CD (change the Z: to your CD drive letter):
      copy Z:\i386\ntldr C:\
      copy Z:\i386\ C:\
4a Sources on the Web (not confirmed by THPC) say that the following must be in \Windows\System32\
      ntdll.dll, ntoskrnl.exe, \config\software, \config\system, and \drivers (can be an empty folder but it must exist).
5. Internet Explorer 7 and recent versions of Windows Media Player will not work after a Reinstall. Uninstall it first and reinstall it later. Read Microsoft's KB917964
6. Service Packs: If your installed Windows contains any Service Pack (SP) more recent than is on your installation CD, you will get the warning "Setup cannot continue because the version ... " and you cannot install. You must uninstall the SP(s) in 'Add/Remove Programs' before reinstalling, or use Autostreamer to create a slipstreamed CD (good idea anyway!) - read How to use Autostreamer.
7. Backup all important data, My Documents, etc. This is important - just in case! Registry backups are in \Windows\Repair.
8. Backup the file \windows\system32\WPA.DBL (and WPA.BAK, if present) to avoid a possible XP Activation.

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How to Start a Repair Installation:

1. Skip to 3 if XP/2K does not boot, or if your 25 character product Key Code is not available right now.
2. If XP/2K boots, boot it up, insert its CD, and click Install
    Accept the Upgrade option.
    You may soon be asked for your 25 character product Key Code!
    Skip to 4.
3. Set the boot order in the BIOS to CD-ROM as first choice (before IDE0 or any hard disk)
    Cold boot from XP/2K's CD (read Boot from a bootable CD if necessary)
    Press [Enter] to Install (do NOT press R to use the Recovery Console)
4. Accept the Licence Agreement
5. Press R to Repair the installed Windows
    Exit immediately if this Repair option is not available
    (if necessary, copy NTLDR and to C: and start again - read 'Preparing ...' above).
    Select the Windows to be repaired.
    Do not interfere with the installation reboots (ignore Boot Menu options).
    Setup will continue as if it was doing a clean install, but your applications and settings will remain intact.
    (expect at least one long apparent pause - note the information screen still changes).
5a If prompted to create new user accounts, create a new account with a different name - delete it later.
6. Reboot when finished and test.
7. Reset the boot order in the BIOS if you altered it (in 3. above).
8. Restore WPA.DBL and WPA.BAK if appropriate. Read XP Activation

Enable your Firewall before establishing an internet connection.

If you find that Windows updates fail to install, use the fix here.

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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