We has this issue last week. Our issue was that we installed ePO as the domain administrator and once we renamed the name of the domain administrator account, we received this message.
We had to go to \\servername\Program Files\McAfee\ePolicy Orchestrator\Server\conf\orion\db.properties and open it with notepad. That is where we saw administrator. We went to the sql server and created a new sql authentcation account for the epo database.