[Samba] Initial replication halts with "The handle is invalid."

[Adam Tauno Williams]

Adding a Windows2008RC to an SerNET S4 4.5.3 (forest level 2008R2)
domain hangs at replication CN=Configuration received 1630 out of
approximately 1663 objects.
 
Only message I can find in the event log on the 2008R2 server is - 

Internal event: The local directory service received an exception from
a remote procedure call (RPC) connection. Extended error information is
not available. 
directory service: 
LARKIN27.micore.us 
Additional Data 
Error value: 
The handle is invalid. (6)

How can one debug where, or on what object, it is hung up or stops?