SERVER2012R2 Std HyperV Host Backups failing

host vm's all have integration services enabled -- (tried disabling but still fails) 

has been working for months with no issue

suddenly 1st vm goes into offline state backing up -- and hangs -- backup never completes (fails - timeout of volumeshadowcopy creation) -- vm doesn't come back online stays offline - critical -- restart of server resolves state of vm --

in vm affected  event22, vss

Volume Shadow Copy Service error: A critical component required by the Volume Shadow Copy service is not registered. This might happened if an error occurred during Windows setup or during installation of a Shadow Copy provider. The error returned from CoCreateInstance on class with CLSID {3e02620c-e180-44f3-b154-2473646e4cb8} and Name SW_PROV is [0x80040154, Class not registered
]. 

list writers -

Writer name: 'Task Scheduler Writer'
   Writer Id: {d61d61c8-d73a-4eee-8cdd-f6f9786b7124}
   Writer Instance Id: {1bddd48e-5052-49db-9b07-b96f96727e6b}
   State: [1] Stable
   Last error: No error

Writer name: 'VSS Metadata Store Writer'
   Writer Id: {75dfb225-e2e4-4d39-9ac9-ffaff65ddf06}
   Writer Instance Id: {088e7a7d-09a8-4cc6-a609-ad90e75ddc93}
   State: [1] Stable
   Last error: No error

Writer name: 'Performance Counters Writer'
   Writer Id: {0bada1de-01a9-4625-8278-69e735f39dd2}
   Writer Instance Id: {f0086dda-9efc-47c5-8eb6-a944c3d09381}
   State: [1] Stable
   Last error: No error

Writer name: 'System Writer'
   Writer Id: {e8132975-6f93-4464-a53e-1050253ae220}
   Writer Instance Id: {e66639b5-a5f8-4f4b-b861-ae17b11be040}
   State: [1] Stable
   Last error: No error

Writer name: 'ASR Writer'
   Writer Id: {be000cbe-11fe-4426-9c58-531aa6355fc4}
   Writer Instance Id: {2481b3e5-2cde-4c10-8d55-24ffbe75d36c}
   State: [1] Stable
   Last error: No error

Writer name: 'Registry Writer'
   Writer Id: {afbab4a2-367d-4d15-a586-71dbb18f8485}
   Writer Instance Id: {9b4e5832-5e68-435b-99c7-75f83cceb514}
   State: [1] Stable
   Last error: No error

Writer name: 'Shadow Copy Optimization Writer'
   Writer Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Instance Id: {8f08e596-407b-4686-ba8e-7d9d943c2a7a}
   State: [1] Stable
   Last error: No error

Writer name: 'COM+ REGDB Writer'
   Writer Id: {542da469-d3e1-473c-9f4f-7847f01fc64f}
   Writer Instance Id: {4283f4f9-76d1-42d7-ba10-0ad1265acfbc}
   State: [1] Stable
   Last error: No error

Writer name: 'BITS Writer'
   Writer Id: {4969d978-be47-48b0-b100-f328f07ac1e0}
   Writer Instance Id: {b9d75626-6d41-40ac-ac82-de0a0fc786dc}
   State: [1] Stable
   Last error: No error

Writer name: 'WMI Writer'
   Writer Id: {a6ad56c2-b509-4e6c-bb19-49d8f43532f0}
   Writer Instance Id: {93a4e0bc-85ea-40e2-a3ac-334b87fdef9f}
   State: [1] Stable
   Last error: No error

listproviders:

Provider name: 'Hyper-V IC Software Shadow Copy Provider'
   Provider type: Software
   Provider Id: {74600e39-7dc5-4567-a03b-f091d6c7b092}
   Version: 1.0.0.0

Provider name: 'Microsoft File Share Shadow Copy provider'
   Provider type: Fileshare
   Provider Id: {89300202-3cec-4981-9171-19f59559e0f2}
   Version: 1.0.0.1

Provider name: 'Microsoft Software Shadow Copy provider 1.0'
   Provider type: System
   Provider Id: {b5946137-7b9f-4925-af80-51abd60b20d5}
   Version: 1.0.0.7

on host

Provider name: 'Hyper-V IC Software Shadow Copy Provider'
   Provider type: Software
   Provider Id: {74600e39-7dc5-4567-a03b-f091d6c7b092}
   Version: 1.0.0.0

Provider name: 'Microsoft File Share Shadow Copy provider'
   Provider type: Fileshare
   Provider Id: {89300202-3cec-4981-9171-19f59559e0f2}
   Version: 1.0.0.1

Provider name: 'Microsoft Software Shadow Copy provider 1.0'
   Provider type: System
   Provider Id: {b5946137-7b9f-4925-af80-51abd60b20d5}
   Version: 1.0.0.7

C:\Windows\system32>vssadmin list providers
vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2013 Microsoft Corp.

Provider name: 'Microsoft File Share Shadow Copy provider'
   Provider type: Fileshare
   Provider Id: {89300202-3cec-4981-9171-19f59559e0f2}
   Version: 1.0.0.1

Provider name: 'Microsoft Software Shadow Copy provider 1.0'
   Provider type: System
   Provider Id: {b5946137-7b9f-4925-af80-51abd60b20d5}
   Version: 1.0.0.7

errors in host event logs -

backup: 

The backup operation that started at '‎2016‎-‎05‎-‎16T02:01:30.898000000Z' has failed because the Volume Shadow Copy Service operation to create a shadow copy of the volumes being backed up failed with following error code '0x80780021'. Please review the event details for a solution, and then rerun the backup operation once the issue is resolved.   (same error every time trying to run backup )

application logs:

Volume Shadow Copy Service error: Unexpected error calling routine RegOpenKeyExW(-2147483646,SYSTEM\CurrentControlSet\Services\VSS\Diag,...).  hr = 0x80070005, Access is denied.
. 




Error5/13/2016 7:32:10 PMMSSQL$MICROSOFT##WID18210Server
BackupVirtualDeviceFile::PrepareToFreeze:  failure on backup device '{D9AAED54-BA8D-4F3D-AEF7-45CB67E09BE3}2'. Operating system error 995(The I/O operation has been aborted because of either a thread exit or an application request.).
. 
Error5/13/2016 7:37:21 PMMSSQL$MICROSOFT##WID5601Server
The service master key could not be force regenerated as requested by the -F startup option. The error number is 33094.

Error5/13/2016 7:37:26 PMVSS8193None
Volume Shadow Copy Service error: Unexpected error calling routine RegOpenKeyExW(-2147483646,SYSTEM\CurrentControlSet\Services\VSS\Diag,...).  hr = 0x80070005, Access is denied.
. 

Operation:
   Initializing Writer

Context:
   Writer Class Id: {35e81631-13e1-48db-97fc-d5bc721bb18a}
   Writer Name: NPS VSS Writer
   Writer Instance ID: {4637a8c2-b018-43d3-b29e-9c59487cef91}

also seeing access denied on WID WRITER & SYSTEM WRITER

ideas of where i should begin?  is this related to vss writers needing to be reregistered or has to do with problems with windows internal database   (hyper-v host is also running remote access services/vpn only