VSS event ID 8194 - correlates with Retrospect Backup activity

I am getting VSS 8194 events in the event log every time the retrospect client kicks of a system backup (including exchange) or a replication process. The retrospect server only reporta one file being incomplete during replication and the backup process reports success except deleted mail boxes (which is expected). I am getting this aince I updated to SP1 and Sharepoint services 3.0. Here is the detailed text :
Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface.  hr = 0x80070005.

I checked the VSS writers with the list command and they all show no errors.

Any advice is greatly appreciated.

Gerd

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