Hi, Just wandering if anyone could help with our problem. We have an Exchange 2007 server all 3 roles are running on the one server. We're having problems with the OAB, all the directories are being created as normal but the OAB.xml file is not being created. There seems to be knowledge bases with similar problems but none of them have helped. I have recreated the autodiscovery service and this seems to be fine when running tests within the Exchange console. I have deleted the virtual directory for OAB and deleted the OAB and recreated all of this from within the console and mmc. Has anyone got any ideas what could be causing this?