When you demote a domain controller that is being used as an Internet Information Services (IIS) 5.0 computer, all applications marked with Application Protection: High (isolated) will fail. The following is an example of an error message that may occur in the Event Viewer's application log:
DCOM got error "Logon failure: the user has not been granted the requested logon type at this computer. " and was unable to logon .\IWAM_servername in order to run the server:
{3D14228D-FBE1-11D0-995D-00C04FD919C1}