Failed to create snapshot for VM, error -3941

Hello

I was hoping some one could explain this error...Failed to create snapshot for [VM], error -3941

I have googled this for a week and was unable to discover any info regarding this message

I am using a VMWare Data Recovery. This virtual has been created new on the esx host [4.1 update 1] 

All other VMs backup correctly [6x2003 and the vmware data recovery VA}

Virtual is a Server 2008 R2 Ent (just file and print services running - IT Department's File Server)

there are two vhds for this server located on two different datastores [due to space/formating issues (all local on the esx host - no SAN)]...

Also some what new to Vmware [Microsoft guru slowly converting]

Thanks for any help