If you wish to install the latest service pack either through windows update or using standalone package,
and you are using a security software , first disable it or best uninstall it and then proceed with service pack
installation. We will try to explain why this is necessary. Before installation starts, the service pack files are
unpacked, some of them can be detected by your security software like malicious ( also called false positive )
and blocked automatically causing service pack installation to fail, your system to freeze or even not be able
to boot at all.
Some security software even if they are disabled using the user guide interface or from startup list (using
msconfig) they will start automatically. This feature is implemented like a prevention method against malicious
files. Even if there are risks involved by uninstalling your security software during service pack install, it's
recommended in order to avoid system crashes..
This is also Microsoft's recommendation.
“Some antivirus software might prevent SP3/SP2/SP1 from installing, or might slow down the
installation.You can try temporarily disabling your antivirus software. If you do so, be sure that you're
aware of the risks involved, and be sure to enable it after the service pack is installed.”