Are there known issues or best practices to install Windows XP Service pack 3 when Symantec Endpoint Protection 11 is installed?
Symantec / Norton KB about your Norton product and XP Service Pack 3 install best practices:
----> This KB is about Norton 2008 products and warns on possible registry keys overwrite by XP Service pack 3 , resulting in one or more of the following symptoms:
* Windows Device Manager is empty
* Missing Wireless network adaptors or other hardware devices
* Unable to connect using a wireless adapter
----> Microsoft Technet forum users noticed Service Pack 3 or Windows Updates failing with Symantec Endpoint Protection 11 (release not specified).
A workaround has been found stopping all Symantec services before running Service Pack 3 setup.
Microsoft Support KB:
http://support.microsoft.com/kb/950717 - Steps to take before you install Windows XP Service Pack 3 (Last Review: April 6, 2009)
The KB warns about some issues that might block Service Pack 3 installation with a generic antivirus software.
There is a warning that disabling the antivirus "may make a computer or a network more vulnerable to attack by malicious users or by malicious software",
but as well is mentioned:
"Although disabling your antivirus software is not usually recommended, some antivirus software prevents certain system files from being changed. This may cause the Windows XP SP3 installation to fail. "