I have a WD Sentinel 4000. It runs Windows Storage Server 2008 Essentials. 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. . This is often caused by incorrect security settings in either the writer or requestor process. Operation: Gathering Writer Data Context: Writer Class Id: {e8132975-6f93-4464-a53e-1050253ae220} Writer Name: System Writer Writer Instance ID: {dc99b3de-ceb1-48d2-8669-8fd43de7fac9} 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'm pretty sure that the correct permissions are there, but obviously I am missing something. Any help would be appreciated. Very respectfully, James Shinevar

Hi, I would like to verify which security software you are running. I suggest you disable Windows Firewall and your security software temporarily, then perform the backup. Meanwhile, the clean boot could be helpful. Niki TechNet Subscriber Support If you are TechNet Subscription user and have any feedback on our support quality, please send your feedback here. Niki Han TechNet Community Support

Hi, I would like to verify which security software you are running. I suggest you disable Windows Firewall and your security software temporarily, then perform the backup. Meanwhile, the clean boot could be helpful. Niki TechNet Subscriber Support If you are TechNet Subscription user and have any feedback on our support quality, please send your feedback here. Niki Han TechNet Community Support

Hi, I am currently standing by for an update from you and would like to know how things are going. If you have any feedback, please let us know. Niki TechNet Subscriber Support If you are TechNet Subscription user and have any feedback on our support quality, please send your feedback here.Niki Han TechNet Community Support

Hi, As this thread has been quiet for a while, I assume the issue has been resolved. At this time, we will mark it as "Answered". If the issue still persists, please feel free to reply this post directly so we will be notified to follow it up. You can also choose to unmark the answer as you wish. BTW, we'd love to hear your feedback about the solution. By sharing your experience you can help other community members facing similar problems. Thanks for your understanding and efforts. Niki TechNet Subscriber Support If you are TechNet Subscription user and have any feedback on our support quality, please send your feedback here.Niki Han TechNet Community Support