Inspiron 9400, Intel Core 2 Duo processor T7200 (OUTLOOK EXPRESS PROBLEM)

Hi,I just bought a new Dell Inspiron 9400/E1705 Laptop. I configured two users in Windows XP Professional 2005 Media center.   I configured Outlook Express 6.0. After configuring O.E. I imported my address book and all my contacts were in my contacts list. I then logged off and clicked on my wife's icon to log onto her desktop. I configured her O.E and upon completion I saw my contacts in her contacts list. So I deleted all my contacts out of her contacts list. I then logged her off and I logged on to my desktop. I opened my O.E. and my contacts that I just imported were deleted also. I went back to my wife's desktop and opened O.E. and imported her email contacts and they went into her contacts lists. I logged her back off and logged onto my desktop and opened my O.E. and her contacts were in my contacts list.I deleted them out of my contact list,and after I logged off and logged back on to my wife's desktop and opened her O.E. her email contacts that I just imported to her contacts list were deleted.So to make a long story shorter...When she  adds a contact to her contact list,it appears in my contact list also. When she or I deleted a contact out of our contact list (like I want my friends in my contact list) but she doesn't...she'll delete them and they automatically get deleted out of my contact list. I called Dell and they told me to call my ISP,then I called my ISP and they told me to call Dell...Dell had me re-format my H.D and reinstall the O.S again,and it still did the same thing with our contacts in O.E.  Any help would be appeciated. Rynnsip