I currently have an AD network, but here is how I got there, then I'll ask my question about the issue I'm having.
1. Took existing NT4 domain and added a new NT4 BDC
2. Promoted new BDC to a PDC
3. Upgraded the OS on the new PDC to Windows Server 2003
4. Added a second AD DC (Both are GCs)
5. Transferred all the FSMO roles to the second AD DC (better hardware, temp machine was used for upgrade)
6. Installed additional 2003 servers for use with running Exchange 2003.
Ok, so now I have AD, internal DNS was setup beforehand. I now have Exchange 2003 on 3 servers installed into an Exchange 5.5 site. Everything is working ok, except for occasionally, maybe once a month, the original AD DC I used to upgrade our domain just freezes. Its pingable, but I can't RDP to the box nor can I interface with system manager. A command line reboot command fails with access denied. Its like all the AD services on the machine just stop, I begin to get LDAP lookup errors and the Exchange SA generates errors about the DC being down or a timeout. Even though I have two AD servers and the box that freezes doesn't even have any FSMO roles on it, only working as a GC. Rebooting the box fixes it for another month or so. The event logs don't contain any errors at all, nothing seems out of the ordinary at all. I'm not sure why we are having these issues. I can't get to the console since its only connected to power and network.
My question is, are there any ideas as to what the problem could be? Anyone else had any similar issues? I'm thinking it could just be the hardware, maybe the server itself is having a problem? Its just weird that I don't see any errors in the event log. It just stops responding as a DC. Any help would be greatly appreciated.