AD Authentication issue in SEPM

Hello,

I'm running SEPM 12.1 on a W2K3 R2 server. We currently authenticate using AD credentials, and the SEPM server is pointing to a W2K3 R2 DC. We are in the process of upgrading our DCs to W2K8 R2. AD is healthy.

When I change my directory servers in SEPM to my new W2K8 R2 DC, I can no longer authenticate/login to SEMP using my AD credentials.

I can login using a "local" admin, and change the Directory Servers back to my original W2K3 DC, and authentication works again.

LDAP is enabled on the newer, W2K8 R2 DC, and I can telnet to the server on port 389.

Why am I having trouble pointing my SEPM console authentication to my shiny new W2K8 R2 DC?

Randy