I have a WD Sentinel 4000. I have 2 laptops that backup to it and both are running Windows 7 Ultimate x64. One laptop backs up perfectly. The other will not backup at all. It fails at 1% and I have VSS errors in the event viewer. This is the error:
Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005, Access is denied.
I have used dcomcnfg to ensure that Network Service has permissions on the laptop. I attempted to reset COM+ using some tutorials online and I think I failed at that so I performed an upgrade install to return the computer to a working state. I still cannot perform the backup. I performed a clean install and still have issues. I'm pretty sure that the correct permissions are there, but obviously I am missing something. Any help would be appreciated.
If you had a 3rd party backup before it can cause this. You said you did a clean instal, you don’t mean the pc and it still fails? Also make sure your WD box has all the windows updates applied