It would help if you could post the message that
they are getting? Is it a network password that is
being requested or ...?

Do you use Exchange Server?

OL: You Continuously Receive Prompts for Your NT Domain Credentials
http://support.microsoft.com/default.aspx?scid=kb%3ben-us%3b321652

I have heard that Outlook 2002 seems to sense that the user's password is
about to expire.

Have the clients press Ctrl-Alt-Del and change password, then log out and
log back in. And they are fine until the password is about to expire
again.

For some reason, about 4 of our users are having problems
with Outlook XP prompting for a password to get in.  I
checked the usual suspect, the security setting for logon
network security, and password authentication is
selected.  We've also tried to re-install office, with no
luck.  Is there a reqistry hack for this?  Is this
problem somehow network related?  ANy imput would be
appreciated.
Thanks,
Gem