o2k profile with upgrd w98 to w2k

Hi,
a machine which was upgraded from win98 to win2k with office2000 installed, after the upgrade when a user logged onto the ads and tried to open outlook, a message appeared ” this application must be reinstalled from the original location”. Even when the a user with admin rights logs on. I have tried to reinstall office 2000 but i then have to do it for all the other users.