Windows 2008 Hyper-V R2 Update for DPM 2010
Hyper-V R2 Update for DPM 2010
Install those two Updates on Hyper-V R2 server:
KB975354 A Hyper-V rollup package dealing with parallel backups on same cluster shared volumes and VM’s hosted by different servers; Avoiding data truncation as a result of simultaneous backup of VM from host and from within virtual machine; properly restoring a VM with snapshots to another location
KB975921 You may be unable to perform certain disk-related operations after an exception when a hardware provider tries to create a snapshot in Windows Server 2008 R2 or Win 7.