Hi Kevin,
In response to your comments the proper way to resolve this issue currently is to ensure that what ever person or script in your environment is disabling users follows the steps as outlined in http://support.microsoft.com/kb/278966
to ensure that the account is properly disable both from and Exchange and Windows stand point. Yes this adds addtional over head to the process. But currently we have no other solution avalible that will ensure that users are disable in a manner that Exchange does not complain about.
The only other options that I can offer is a utility called Nomas. You will need to contact Microsoft Support in order to get the utility but it will read your domain and correct any and all users that are in this condition.
The following link can provide you with more inforamtion:
http://support.microsoft.com/kb/555410/en-us
-Matt