Issues installing KB 973917 on Windows Server 2003

Some customers have reported issues of application pools unable to start after applying KB 973917 on Windows Server 2003 to add support for Extended Protection in Windows Authentication. The root cause of this issue is machines being in an unsupported state where SP1 version of IIS binaries exist on an SP2 installation. Product support has released KB 2009746 on how to resolve this issue. The summary of the resolution is to reinstall SP2 to such machines to update all IIS binaries to the SP2 version.