How to Enable DCpromoUI Logs

The Dcpromoui.log file captures status information on the promotion or demotion of an Active Directory computer from start to finish, including the capture of user input for the role the server will play in the forest.

221254 Registry Settings for Event Detail in the Dcpromoui.log File
http://support.microsoft.com/?id=221254

Value Path: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\AdminDebug
Value Name: DCPromoUI
Value Type: REG_DWORD
Value Data: FF0003 (hex)
Output: %systemroot%\debug\dcpromoui*.log