How to find out why credentials have expired

[neelsmail@rediffmail.com]

Hi,

I am using Kerberos 5 to authenticate an AD user from Linux RHEL 5.1
with NetworkManager installed. Every so often, a dialog box pops up
which asks for the credentials of the AD user. I wanted to know how
can I find out why and how his credentials have expired. Is there a
way to do that?

Thanks,
Neel.