Mail items disappear from Outlook 2007 deleted items box after 7 days

I am a system administrator. We are running Exchange 2003 server back end with Outlook 2007 on our desktops. I have a user who’s deleted items are removed from her deleted items box of outlook after 7 days. I have turned off her autoarchieve feature. I’ve disabled permanent delete in Outlook. I’ve changed her deleted retention in Exchange to 365 days, but the items still are deleted after 7 days. I tried setting an autoarchieve to archieve the deleted items after 6 days but that didn’t work either. I’ve rebuilt the .OST file from scratch. No other users are having this problem and I’m using the same retention policy for all. Any suggestions on where else the problem might be?