"Access Is denied" Error Message When You Try to Install Windows XP Service Pack 1

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:

When you upgrade from Microsoft Windows XP to Windows XP Service Pack 1 (SP1) or later, you may receive the following error message:

This problem may occur if the user does not have full control permissions to the following registry key:

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 resolve this problem, give the Administrators group Full Control permissions to the Auto Update registry key. To do so, follow these steps:

1. Make sure that you use an account that has administrative credentials to log on to the Windows XP computer.
2. Click Start, click Run, and then type the following command:
   regedit
3. Click OK.
4. Locate the following key in the registry:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update
5. Right-click the Auto Update folder, and then click Permissions.
6. Make sure that the Administrators group has Full Control.