Make sure you are upgraded to the latest version of Enzoic for Active Directory as well as the Enzoic for Active Directory Client. Starting in builds 3.3.135 this is no longer a problem. You can find the latest builds linked below:

Setup Instructions - Enzoic for Active Directory 

Custom credential providers by default can suffer from this behavior. So if somehow you ended up here and are not using the Enzoic Workstation Client, check to see if you are using a custom credential provider that could be causing this behavior.