Su to root

[Clemente Armando B. (esm1abc)]

Folks,
Within the past month or so, I have had a couple of users "su" to root
without knowing the roots password. The user was instructed to change their
user password and upon entering the new password, I was "beeped" by the
system that an unauthorized user "su  to root". The users normal process is
to log in to their P.C. and run a Microsoft Access inquiry to the HP-UX UNIX
server where the user id and password are authenticated. Upon questioning
the user, the user had no idea what they had done. The are not UNIX trained
individuals. If anyone has any ideas or thoughts, please let me know.
Thank you,
Armando