Where are you seeing the KB number reported as the missing update? When OneCare checks for missing updates from Windows Update and it finds that there are offered critical/important updates that are not installed, it only advises you to visit Windows update, it does not tell what update is missing.
In any event, this isn't a OneCare issue, it is a Windows Update issue. There is a fix noted within this thread:
http://groups.google.com/group/microsoft.public.windowsupdate/browse_thread/thread/ae4b673536f78714/70e9df53fbe96a31?show_docid=70e9df53fbe96a31You can pursue this with Microsoft Support for free since it is a Windows Update problem:
Windows Update Solution Center - http://support.microsoft.com/ph/6527
-steve
Microsoft MVP Windows Live / Windows Live OneCare & Live Mesh Forum Moderator