I've had that happen to me before, but I'm not sure how I fixed it. If she's running OE at home, that might be the problem, although that's just a stab in the dark.
csamuels posted this in another thread, this might be a clue for what you're looking for.
"pull up the account properties and click the advanced tab and check leave a copy of messages on the server."
*\'Failure\' is not a four-letter word.