unable to create static copy of active snapshot - win server 2k8

hey gents - having an odd problem here - after a few weeks of normally functioning, fdisr is now giving me the error "unable to create static copy of active snapshot"

the odd thing is, when i reboot, fdisr always allows 1 proper copy of the snapshot, but always on the second or subsequent attempts i get the abovementioned error.

i havent really changed anything per se and i have no realtime security software running, so im stumped - anyone have any ideas?

thanks!

 

looking in event viewer, Volume Shadow Copy Service has this error occur:

Volume Shadow Copy Service error: Unexpected error DeviceIoControl(\\?\Volume{ec73c3c2-a22c-11e1-bd9d-806e6f6e6963} - 0000000000000148,0x0053c020,00000000001CBC40,0,00000000001CA6E0,4096,[0]). hr = 0x80070057, The parameter is incorrect.
.

Operation:
Automatically choosing a diff-area volume
Processing EndPrepareSnapshots

Context:
Execution Context: System Provider