Administartor account renamed “disabled”

On My PCD The Administrator account’s pre win 2k compatable name has been changed to “disabled”. I am running a mixed network of multiple Win OSs. I have tried to renam it Administrator, it holds for couple of min.s then reverts. I can log in locally using disabled as the username and the same password. But not as Administrator. Is there a registry hack for this?? Or a way to get around this.????