Security Update for Windows XP KB923561 failed to install

in addition, when i shut down my home computer, running windows xp home
edition, it always has that icon that means there's an update that needs to
be installed. it happens every day, which, to me, means it didn't work each

and every couple of days or so, the yellow shield icon comes up on the lower
right and prompts me to install a security update and it fails every time.
and it's always kb923561.