I have a hyper-v cluster operating on win2k8 R2 in a 2003 forest. These servers are at our NOC with a DC that connects to our PDC at HQ via a persistent VPN. The cluster boxes are reporting a error event ID 1006 shown below. The DC is also reporting an error 5805 also shown below. I have found numorus posts regarding 1006 errors, but none for error ID 52's. It's weird, I can ping and I can browse network shares on the DC from each. I thought maybe a DNS or net work issue, but nslook up works too.

Event 1006

 <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
 <System>
 <Provider Name="Microsoft-Windows-GroupPolicy" Guid="{AEA1B4FA-97D1-45F2-A64C-4D69FFFD92C9}" /> 
 <EventID>1006</EventID> 
 <Version>0</Version> 
 <Level>2</Level> 
 <Task>0</Task> 
 <Opcode>1</Opcode> 
 <Keywords>0x8000000000000000</Keywords> 
 <TimeCreated SystemTime="2013-12-17T00:08:19.582292600Z" /> 
 <EventRecordID>41808</EventRecordID> 
 <Correlation ActivityID="{26B10592-6228-4A3E-845B-E04B49702A54}" /> 
 <Execution ProcessID="964" ThreadID="1384" /> 
 <Channel>System</Channel> 
 <Computer>NEOREEFVH1.neoreef.com</Computer> 
 <Security UserID="S-1-5-18" /> 
 </System>
 <EventData>
 <Data Name="SupportInfo1">1</Data> 
 <Data Name="SupportInfo2">5012</Data> 
 <Data Name="ProcessingMode">0</Data> 
 <Data Name="ProcessingTimeInMilliseconds">1138</Data> 
 <Data Name="ErrorCode">52</Data> 
 <Data Name="ErrorDescription">Unavailable</Data> 
 <Data Name="DCName" /> 
 </EventData>
 </Event>

Event 5805

 Event Type:    Error
 Event Source:  NETLOGON
 Event Category:    None
 Event ID:  5805
 Date:      12/16/2013
 Time:      2:32:01 PM
 User:      N/A
 Computer:  NEOREEFSRV15
 Description:
 The session setup from the computer NEOREEFVH3 failed to authenticate. The following error occurred: 
 Access is denied. 

 For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
 Data:
 0000: 22 00 00 c0               "..À    

Here are the networks on the hosts:

Any with a "Enabled" Are virtual switches.