Event ID 8194 is logged in the Application log when you install the 2007 Office system on a Windows Vista-based computer

When you install the 2007 Office system on a Windows Vista based computer, the following event is logged in the Application log:

Log Name: Application
Source: VSS
Date: DateTime
Event ID: 8194
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: ComputerName
Description:
Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005. 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: {51ff0833-99d7-4f35-b8f9-0495ceff2a24}

Additionally, the same event may be logged when you uninstall the 2007 Office system.

The Setup program for the 2007 Office system creates a restore point. This restore point enables users to roll back the system to the state that existed before the installation. To create the restore point, the Setup program uses Volume Shadow Copy Service (VSS). VSS determines that there has been a System Writer failure, and then it logs the error that is mentioned in the "Symptoms" section. However, the Setup program is completed successfully and the restore point is created successfully. Therefore, you can safely ignore the event that is logged in the Application log.

You can safely ignore this event.