infected XPs not patched

[BBC news 2010 April 16] "Some of the latest security updates for Windows XP will not be installed on machines infected with a rootkit virus.  A rootkit is sneaky malware that buries itself deep inside the Windows operating system to avoid detection.  Microsoft said it had taken the action because similar updates issued in February made machines infected with the Alureon rootkit crash endlessly. The latest updates can spot if a system is compromised by the Alureon rootkit and halt installation."