[Samba] linux server not caching users

[Lee, Steven P]

I've got a CentOS 5 server joined to a Windows 2003 Domain.

The Linux machine joined the Windows domain successfully and imported
users, created their home directories and migrated their passwords.

When looking at the current home directory
It lists permissions and ownership properly for a few minutes

drwxr-xr-x  2 jdoe 	domain users 	4.0K Jun 14  2007 jdoe
drwxr-xr-x  2 jqpublic 	domain users	4.0K May 23  2007 jqpublic

after a few minutes running the command whoami and crontab fails and
looking at the home directory shows the userid number as opposed to the
usernames

drwxr-xr-x  2 16785470 16777729 4.0K Mar 27  2007 jdoe
drwxr-xr-x  5 16785433 16777729 4.0K Jun  2 10:27 jqpublic

running getent will reacquire the usernames allowing whoami to work
again.

Any help is appreciated.