Microsoft recently released the SP3 (Service Pack 3) update for Windows XP, and many of us have experienced major issues attempting to install the update. Microsoft released an article discussing the issue, which can cause you to receive a "Access Denied" error when attempting to install the update. The most frustrating part of the issue is that it happens 30 minutes into the process, which you have to completely re-start in order to try again.
So here's how you fix it! You can reference these instructions in detail at Microsofts Knowledge Base here:
http://support.microsoft.com/kb/949377
How to Install Windows XP SP3 Service Pack 3 and avoid Access Denied errors
1) Download the Service Pack Installation file here:
2) Backup your Registry (this is suggested but not required)
322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows
3) Install Subincl.exe (Free Microsoft Utility Product)
4) Create a Text File called Reset.cmd in Notepad with the following content
cd /d "%ProgramFiles%\Windows Resource Kits\Tools"
subinacl /subkeyreg HKEY_LOCAL_MACHINE /grant=administrators=f /grant=system=f
subinacl /subkeyreg HKEY_CURRENT_USER /grant=administrators=f /grant=system=f
subinacl /subkeyreg HKEY_CLASSES_ROOT /grant=administrators=f /grant=system=f
subinacl /subdirectories %SystemDrive% /grant=administrators=f /grant=system=f
subinacl /subdirectories %windir%\*.* /grant=administrators=f /grant=system=f
secedit /configure /cfg %windir%\repair\secsetup.inf /db secsetup.sdb /verbose
5) Run the Reset.cmd file (and wait 10-30 minutes)
6) Run the SP3 Installation File
