We have recently upgraded our network and have been having constant problems since with DNS and replication.
We started with a 2003 DC running DHCP, DNS and all FSMO roles. We have built a VM 2008 DC, upgraded the forest schema and transferred all FSMO roles to this new 2008 DC. DNS has been setup and configured on this server as an AD Primary.
The 2003 DC is still online but not contactable as i have disabled the NIC until happy to dcpromo and decom from the domain.
This morning we had an issue with a VIP logging on and his profile not loading. The admin account would not show his profile on the local laptop at all in any root. Renaming his profile and logging on again only gave him a temp account. He has no roaming profile configured. We quickly realized that connection to the file server (where his user data is stored) was contactable by rdp, ping to ip and hostname but browsing to it did not show the shared folders.
Therefore i rebooted the main DC and all other servers there after. I gave his laptop a static IP outside the DHCP scope and rebooted. This resolved the issue with the missing profile, but doesn't explain what happened in the first place. I believe this is something to with the DNS issues we are having but cant see what I'm missing.