Windows 2003 DC

My Windows 2003 servers crash when I promote them to a DC. I have had 2003 servers as my DCs for quite a while and now all of a sudden they can’t do this. My 2000 servers are working fine as DCs but I want to put my 2003 servers back in as DCs. I have a feeling there may be something wrong in my active directory that may be causing it but don’t have any idea where to start looking. We have not done anything lately in AD that would have caused this.