Description of problem:
I tried to create a shadow copy of a single disk on a windows VM, using qemu-guest-agent via vshadow tool.
This attempt failed with this error (on the windows guest):

Error during the last asynchronous operation.
- Returned HRESULT = 0x8004230f
- Error text: VSS_E_UNEXPECTED_PROVIDER_ERROR
- Please re-run VSHADOW.EXE with the /tracing option to get more details

Version-Release number of selected component (if applicable):
is26
Windows server 2008 64bit
rhevm-3.3.0-0.37.beta1.el6ev.noarch
qemu-ga-win-6.5-4

How reproducible:
100%

Steps to Reproduce:
1. install a windows VM with 3 disks and rhevm-guest-tools with the mentioned qemu-guest-agent version which support vss for windows.
2. install Volume Shadow Copy Service SDK 7.2 on the guest. Check the providers list:
C:\Program Files (x86)\Microsoft\VSSSDK72\TestApps\vshadow\bin\obj-fre\amd64>vss
admin list providers
qemu-guest-agent is suppose to be the main provider:

vssadmin 1.1 - Volume Shadow Copy Service administrative command-line tool
(C) Copyright 2001-2005 Microsoft Corp.

Provider name: 'QEMU Guest Agent VSS Provider'
   Provider type: Software
   Provider Id: {3629d4ed-ee09-4e0e-9a5c-6d8ba2872aef}
   Version: 0.12.1

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

3. create a shadow copy using vshadow command on the guest:

C:\Program Files (x86)\Microsoft\VSSSDK72\TestApps\vshadow\bin\obj-fre\amd64>vsh
adow.exe e:


Actual results:
Shadow copy creation fails on the guest with this error on the event logs:

Volume Shadow Copy Service error: Error calling a routine on a Shadow Copy Provider {3629d4ed-ee09-4e0e-9a5c-6d8ba2872aef}. Routine details GetSnapshotProperties({7f97ecd6-b278-4057-abbf-d67cd1db2334}) [hr = 0x80042308].

Expected results:
It should be possible to create a shadow copy of a disk on a windows machine using the qemu-guest-agent as a vss provider.

Additional info: Screenshots, event log and engine.log