Server 2012 - VSS Event ID 8194 - Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005 Access is denied

I'm seeing an error popping up in the application log on both nodes of my Server 2012 cluster.  The events seem to occur when DPM begins a system state/bmr backup of the node.  The DPM Backups usually complete successfully, but over the course of a sync or consistency check this event might appear 8-10 times in the application log of the cluster node.  The event reads:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event"><System><Provider Name="VSS" /><EventID Qualifiers="0">8194</EventID><Level>2</Level><Task>0</Task><Keywords>0x80000000000000</Keywords><TimeCreated SystemTime="2013-05-13T05:15:50.000000000Z" /><EventRecordID>11424</EventRecordID><Channel>Application</Channel><Computer>node1.domain.com</Computer><Security /></System><EventData><Data>0x80070005, Access is denied.</Data><Data>

Operation:
   Gathering Writer Data

Context:
   Writer Class Id: {e8132975-6f93-4464-a53e-1050253ae220}
   Writer Name: System Writer
   Writer Instance ID: {c9b83054-b318-4486-a5aa-6c36b591b3f8}</Data><Binary>2D20436F64653A20575254575254494330303030313330302D2043616C6C3A20575254575254494330303030313235342D205049443A202030303030313631362D205449443A202030303031353238382D20434D443A2020433A5C57696E646F77735C73797374656D33325C737663686F73742E657865202D6B204E6574776F726B53657276696365202020202020202D20557365723A204E616D653A204E5420415554484F524954595C4E4554574F524B20534552564943452C205349443A532D312D352D3230</Binary></EventData></Event>

If I run 'vssadmin list writers' after the backup job completes, all writers report their state as stable with no errors.  

I came across this error recently when trying to troubleshoot another issue, but looking back, I can see that these have been going on for a while.  The first instance I see occurred in early March.  

Any suggestions on what I can do to clear up this error?