ADSI: error 8250 “the server is not operational”
This error can be generated when the domain controller you use in scripting suffers from sub-optimal performance. In bulk scripts when lots of requests are done on a single domain controller, ADSI can generate this error. If the domain controller you are using is virtualized, try performing the same operation on a physical domain controller.
Also, on Small Business Server, try to start the RPC Locator service. The RPC Service is always started automatically but the RPC Locator service isn’t.