I have two SBC 2003 and I have lot’s of problem

I made the second SBC2003 as a member of a domain which domain controller is also sbc2003
but the damn thing keep telling me you must finish installation and make this server also a domain contrller, otherwise it keep shutting down . I did that and then it said . two sbc2004 can not be both domain controller !!! and again keep shutting down . what a waste of money? can somebody help me on this matter ?