runtime error 424

in windows XP

after start up we get an error message that says
monitorstart: unable to set talkback system hook also a
run time error
'424' and also when I click on contol panel in the start
menu I get a
window that pops up which says Explorer failed to get data
for 'AC'. I
can't figure these messages out. I tried to reinstall
drivers and
applications that didn't work and I tried to reinstall
yahoo DSL
software that doesn't help. It seems all this started
after we got the
DSL.I tried a system restore that didn't work.Anti virus
scanned didn't
show any viruses, I have eTRUST EZ ARMOR antivirus that
comes with the
Yahoo DSL and also I have Zone Alarm for a fire wall which
was also
downloaded through the DSL. I've tried all I know, which
is limited, but
nothing worked.