Is this snap vmware synchronized, MS VSS synchronized or neither? If vmware synchronized try the following test...
1. take a snap in vmware (not fro the Nimble) uncheck both boxes (snap memory and quiesce file system, bot unchecked). Is it succesful?
2. Do the same but quiesce the filesystem. Is it succesful?
If no to 1 and 2, call vmware.