Too many .pst files

[RoN]

Greetings,
I have just used the custom maintenance wizard to
automatically set up my users' pop mail accounts (all they
have to do is logon to the machine, doubleclick Outlook
and all of their user & mail server info is automatically
inputted) using outlook 2002.
It worked well in theory, but everytime my users logon
and open outlook 2002, another .pst file is created (ie
outlook.pst, outlook1.pst, outlook2.pst etc), therefore
their sent messages, addressbooks etc go missing.
Why does outlook 2002 keep creating these new pst files,
and how can I stop this in the future?

Thanks,
RoN