When you attempt to install Windows 2000 SP3/SP4 on a computer that has the Distributed Component Object Model (DCOM) default impersonation levelĀ  set to Anonymous, the install fails and you receive:

An error in updating your system has occurred.

If you subsequently try to install a program that uses Windows Installer packages (.msi files), you may receive a message similar to:

The Windows Installer Service could not be accessed.
This can occur if you are running Windows in safe mode, or if the Windows Installer is not correctly installed. Contact your support personnel for assistance.

The failed SP3/SP4 install places Windows Installer version 2.0.2600.2 on your computer, but it is disabled.

To workaround this problem:

1. Open a CMD prompt and type dcomcnfg.

2. Select the Default Properties tab.

3. Press Identify in the Default Impersonation Level drop-down list.

4. Press OK.

5. Type:

ren %windir%\system32\msisip.dll msisip.old

6. Install Windows 2000 SP3 or SP4.

NOTE: You can download Windows Installer version 2.0.2600.2 from http://www.microsoft.com/downloads/release.asp?ReleaseID=32832.