The MS KB article discussed above is no longer available. It said:
You receive an "Access is denied" error message when you try to install Windows XP Service Pack 2
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Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
SYMPTOMS
When you try to install Microsoft Windows XP Service Pack 2 (SP2), you may experience the following issues:
You cannot install the service pack.
You receive the following error message:
Service Pack setup has failed. Access Denied
The Setupapi.log file contains references that indicate that one or more registry keys could not be deleted while the Setup program was running.
CAUSE
These issues may occur when permissions on one or more registry keys are restricted in a way that prevents the administrator who installs the update from updating the registry keys. Failure to update a registry key causes the Setup program to fail.
WORKAROUND
Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.To work around this issue, examine the Svcpack.log file to find the registry keys that are causing this issue, and then modify the registry permissions to give access to the user who is trying to install the service pack. To do this, follow these steps:
Make sure that the user who is trying to install the service pack is a member of the Administrators security group.
Open the Svcpack.log file. By default, this file is located in the C:\Windows folder.
Search the log file for references to registry permissions issues. Make a note of the registry keys that are referenced.
Click Start, click Run, type regedit, and then click OK to start Registry Editor.
Locate and right-click the registry keys that you noted in step 3 of this procedure, and then click Permissions.
Examine the permissions that are configured for each user or group. Identify the restricted permissions that are affecting the user who is trying to install the service pack. Make sure the Administrators group has full access configured.
Quit Registry Editor.
After you follow these steps, try again to install the service pack.
The information in this article applies to:
Microsoft Windows XP Home Edition Service Pack 2 (SP2)
Microsoft Windows XP Professional Service Pack 2 (SP2)
Last Reviewed: 8/26/2004 (2.1)