Exchange 2007 LCR with DPM 2007

You need to disable the VSS replica Writer on that LCR DB by registry and restart the services
add the EnableVssWriter key as a DWORD with a value of 0 under
HKLM\Software\Microsoft\Exchange\Replay\Parameters
then restart the Microsoft Exchange Replication Service

http://technet.microsoft.com/en-us/library/bb795725.aspx