Exchange 2007 Transport Service Stops

Hello,
We recently demoted an old DC running Server 2003 to raise our Forest & Domain Functional Level to 2008 R2. We had added a 2008 R2 domain controller and tested running with that before demoting the old server without any issues with the domain or our Exchange 2007 server. But since demoting the 2003 server and raising the functional levels on the domain we've had issues with the Exchange 2007 machine (Server 2008 not R2) and the Transport service stopping. We now only have the one DC, the Server 2008 R2 machine.  

The first error that happens:
Source: MSExchangeADAccess
EventID: 2102
Process MAD.EXE (PID=3972). All Domain Controller Servers in use are not responding: <ourdc>.<domain>.local

That error happens a few times before this error, where the transport service stops:
Source: MSExchangeTransport
EventID: 12009
Microsoft Exchange couldn't read the Receive connector configuration because the directory is unavailable. The service will be stopped.

All the microsoft articles say to make sure the exchange server can communicate with the DC. There should be nothing preventing them from communicating. The one Microsoft artilce says to make sure that the exchange server is in the policy to "Manage auditing and security logs", which it already is in there. Running DCDIAG it fails in 2 spots, NCSecDesc which from what I read there should be nothing to worry about. And the other spot DCDIAG fails is Services. One article I found said to start the RPC Locator service on the DC, but that didn't seem to resolve the error from DCDIAG. Any help on the issues would be greatly appreciated.