Promoting an Exchange Server to a Domain Controller and consequences

I originally was having a problem with my Exchange 2007 box not updating the OAB correctly, and after much heartache I found it was an issue with LDAP and authenticating to itself. So I performed a dcpromo.exe on the exchange box, which fixed the problem. Now (a month or so later) I’m getting issues where people are getting locked out of their accounts for no reason. After looking at the server’s they are getting locked out of, it is the main AD server ADS02 and the exchange box EXC02. Any ideas of why this is happening or how to fix?

Thanks,
Joe