This is a bit of a strange issue and I haven't been able to find any evidence of similar reports. Maybe someone smarter than myself can point me in the right direction.
I have been having trouble making quiesced snapshots with one of our linux virtual machines. Unquiesced snaps seem to work fine(but are not ideal). I have installed the latest vmware-tools and enabled the vmsync driver at install. But whenever I attempt a quiesced snapshot it fails almost immediately. I enabled debugging for vmware-tools, and below is a excerpt from that logfile.
2013-02-27T12:12:12.308Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackupStart
2013-02-27T12:12:12.309Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] Using quiesceApps = 1, quiesceFS = 1, allowHWProvider = 1,execScripts = 1, scriptArg = , timeout = 0
2013-02-27T12:12:12.310Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] Quiescing volumes: 6000c29b-23e2-4437-2bc4-8f029c478d2a 6000c296-e56b-2ffd-621c-d810d75487fe
2013-02-27T12:12:12.310Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackup_SendEvent
2013-02-27T12:12:12.311Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackupStartScripts
2013-02-27T12:12:12.312Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] Trying to run scripts from /etc/vmware-tools/backupScripts.d
2013-02-27T12:12:12.312Z| vcpu-0| I120: ToolsBackup: changing quiesce state: IDLE -> STARTED
2013-02-27T12:12:13.312Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackupAsyncCallback
2013-02-27T12:12:13.312Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] VmBackupAsyncCallback: checking VmBackupOnFreeze
2013-02-27T12:12:13.313Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] Async request 'VmBackupOnFreeze' completed
2013-02-27T12:12:13.313Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackupEnableSync
2013-02-27T12:12:13.313Z| vcpu-0| I120: Guest: [ info] [vmsvc:guestinfo] Poll loop disabled.
2013-02-27T12:12:13.313Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackupSyncDriverStart
2013-02-27T12:12:13.313Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmsvc] SyncDriver: Freezing using Linux ioctls...
2013-02-27T12:12:13.314Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmsvc] SyncDriver: failed to open '6000c29b-23e2-4437-2bc4-8f029c478d2a': 2 (No such file or directory)
2013-02-27T12:12:13.314Z| vcpu-0| I120: Guest: [ warning] [vmsvc:vmbackup] Error freezing filesystems.
2013-02-27T12:12:13.314Z| vcpu-0| I120: Guest: [ info] [vmsvc:guestinfo] New poll interval is 30s.
2013-02-27T12:12:13.314Z| vcpu-0| I120: Guest: [ debug] [vmsvc:vmbackup] *** VmBackup_SendEvent
2013-02-27T12:12:13.314Z| vcpu-0| I120: Msg_Post: Warning
2013-02-27T12:12:13.314Z| vcpu-0| I120: [msg.snapshot.quiesce.vmerr] The guest OS has reported an error during quiescing.
2013-02-27T12:12:13.314Z| vcpu-0| I120+ The error code was: 3
2013-02-27T12:12:13.314Z| vcpu-0| I120+ The error message was: Error when enabling the sync provider.
2013-02-27T12:12:13.314Z| vcpu-0| I120: ----------------------------------------
Any help would be greatly appriciated!