insist that she LOGS OUT as a minimum

have you ran the updates ?
set auto update to D/L but to install only when you say.....

my first instinct was the auto update failing
suspect S/W corruption

if it's a work machine, and the image is standard
re-image

if the image is not standard, then run a repair with an XP cd
that is to go on till it asks whether you want to install a fresh version OR repair

choose repair