admin rights not working

A friend asked me to look at her XP computer. She is not able to do certain
things or access certain areas without a message coming up saying she does
not have Admin rights. I opened the control panel and she is listed as the
only user and with full admin rights. I tried again but had no luck. One
thing I was trying to do was get into Documents and Settings but was
blocked. I then changed her account settings so she had to use a password
to log on. Requiring the password changed nothing. She is still blocked
from some areas.

I do not know what Service Package she is up to. She told me she does do
the updates, but I forgot to check.

What am I doing wrong? How can XP say she has full admin rights and then
say she can not do something since she does not have full rights?