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.