Imagine this scenario: You’ve been troubleshooting a nasty problem with Windows 2000 that has rendered the system unbootable by standard means. You’ve been able to access the Windows 2000 Advanced Options menu, and you’ve tried both the Safe Mode and Last Known Good Configuration options—neither worked. So you went to the next level and broke out your Emergency Repair Disk (ERD) and attempted to revive the system by running an Emergency Repair Process. That, too, ended in failure.

So now what do you do? Reformat the hard disk and reinstall the operating system from scratch? There’s one more operating-system salvage technique that you can try before you have to take the drastic step of reformatting and reinstalling. This technique involves performing an in-place upgrade.

Works for both versions

The Windows 2000 in-place upgrade procedure described here applies to both Windows 2000 Professional and Windows 2000 Server. For my example, I’ll be performing the in-place upgrade for Windows 2000 Professional.

Complete reinstallation is sometimes the way to go
Before you get started, I warn you that performing a Windows 2000 in-place upgrade isn’t a quick operation. In fact, the entire procedure could potentially take as long as it would to reinstall the operating system from scratch. If you have a recent backup, or there’s really no irreplaceable data to lose on the hard disk and few applications to reinstall, you may want to consider going ahead and reformatting the hard disk and reinstalling Windows 2000 from scratch.

What doesn’t change
Performing an in-place upgrade operation leaves as much of the existing operating system configuration in place as possible. All of the standard Windows components you’ve installed will remain. And any of the standard Windows components you chose not to install when you initially ran Setup will not suddenly appear. All of the applications that are installed on the system will remain in working condition. This means that none of the application-related entries in the registry will be changed.

None of the passwords will be changed. Once the operation is complete, you’ll be able to log in and access all the same network resources you did prior to performing the in-place upgrade operation. The role of the computer won’t change. In other words, a Windows 2000 server system configured as domain controller won’t reemerge from an in-place upgrade operation as a member server.

What does change
Of course, performing an in-place upgrade operation does indeed revert a lot of the operating system to the base, right-out-of-the-box configuration. The registry will be refreshed and the default operating system values will be restored. This means that any hot fixes and service pack updates you’ve installed will be rendered null and void. In addition, Internet Explorer, which is an integral part of the operating system, will revert to its initial version.

All Component Object Model (COM) components and Windows File Protection (WFP) files will be reregistered. Every Plug and Play device will be reenumerated, including the hardware abstraction layer (HAL). All drive letters that exist at the time of the in-place upgrade operation will be reenumerated. This means that some drive letters may be changed by Windows 2000’s Mount Manager (MountMgr) program. (If this is of concern to you, see the Microsoft Knowledge Base article 234048, “How Windows 2000 Assigns, Reserves, and Stores Drive Letters” for more details.) In addition, all of the original default permissions will be reapplied.

Dealing with user profile changes
If the system on which you’re performing the Windows 2000 in-place upgrade was originally upgraded to Windows 2000 Professional from Windows NT 4.0 Workstation, be aware that the in-place upgrade procedure will change the registry values associated with the location of the user profiles. Windows NT 4.0 Workstation stores user profiles in the C:\Winnt\Profiles folder. When you upgrade to Windows 2000 Professional on top of Windows NT 4.0 Workstation, Setup leaves the user profiles in that folder rather than moving them to the location that Windows 2000 Professional normally uses—C:\Documents and Settings.

However, when you perform a Windows 2000 in-place upgrade, the procedure creates a C:\Documents and Settings folder and points the registry profile settings to this folder. You’ll need to edit the registry and change the entry that references the path for the user profiles, then change it back to C:\Winnt\Profiles. Launch the Registry Editor and open the HKEY_LOCAL_MACHINE key. Then, subsequently open each of the following keys:

Windows NT

Once you open the ProfileList key, you’ll find a group of keys named after SID numbers. Open each one and check the ProfileImagePath string value until you find those that reference the user profiles. Then, update each one to point to %SystemRoot%\Profiles\<UserName>.

Performing the in-place upgrade operation
Performing the Windows 2000 in-place upgrade is a pretty straightforward procedure. You can initiate the operation from a set of Windows 2000 boot disks or, if your system is capable of booting from a CD, straight from the Windows 2000 CD. Since most systems are capable of booting from a CD, that’s the path I’ll follow in my example.

Insert the Windows 2000 CD into the drive, restart your system, and boot from the CD. Once the initial preparation is complete, you’ll see the Windows 2000 Professional Setup screen, as shown in Figure A.

Figure A

To initiate the in-place upgrade, press [Enter] to launch the Windows 2000 Professional Setup procedure. When you see the License Agreement page, press [F8] to acknowledge that you agree. Setup will search the hard disk looking for a previous installation of Windows 2000. Once it finds the previous installation, you’ll see a Windows 2000 Professional Setup screen like the one shown in Figure B.

Figure B
When Setup locates the previous installation, you’ll be prompted to initiate the in-place upgrade.

As you can see, this second screen prompts you to press R to repair the selected installation or to press [Esc] to install a fresh copy of Windows 2000. In this case, initiating a repair operation is synonymous with performing an in-place upgrade, so you’ll need to press R.

Setup will examine the disk drives in the system and will then begin performing the in-place upgrade. As I mentioned, this procedure may take a considerable amount of time. Once the in-place upgrade procedure completes, Setup will restart the computer. If everything went well, Windows 2000 should be in good working order.

Reupdating your system
As I mentioned in the “What does change” section, performing an in-place upgrade operation does revert a lot of the operating system to the base configuration. Most important, this means that you’ll need to reapply all of the current hot fixes and service pack updates to your rebuilt Windows 2000 installation.

The first order of business is to access the Windows Update site and allow the service to scan your system for updates. You can then download and install all the necessary updates. Once you finish with Windows Update, you can reconfigure any of the other operating system settings that were changed as a result of performing the in-place upgrade.

Special considerations for Windows XP
Chances are that in addition to supporting Windows 2000 systems, you’re also supporting Windows XP systems. You may have wondered about performing a Windows XP in-place upgrade. When you’re troubleshooting problems on a Windows XP system, you have the added luxury of the System Restore feature, which allows you to easily revert your system to a point in time before the problem occurred and when the system was in a good stable condition. You really shouldn’t need to perform a Windows XP in-place upgrade.

However, if you’re unable to gain satisfactory results from System Restore, you can indeed perform an in-place upgrade in Windows XP. The steps you’ll take are identical to the ones for Windows 2000. The end results are almost identical. However, in addition to the changes I listed, in Windows XP you’ll also lose all your existing restore points as well as any backup copies of the registry created by using the Backup utility to back up your System State.

In addition, if your system came preinstalled with Windows XP, investigate Microsoft Knowledge Base article 312369, “You May Lose Data or Program Settings After Reinstalling, Repairing, or Upgrading Windows XP,” before you undertake an in-place upgrade.