mailbox store in exchange system manager 03 is not updating correctly

We have Exchange server 03 installed on windows server 2003 SP2. The mailbox store in exchange system manager is not updating very quickly. IT has been about 12 hours and still has not updated. I believe all updates have been installed for the server and exchange services. We have storage limits set and users are not able to send out mail once the limit is met. They clean out there mailbox and are still unable to send emails out because system manager is not updating quickly. any help is much appreciated!