Symptoms
When the client was using the Archiving tool in the workspace they saw the following error...
"Error Occurred:Invalid column name 'Identity'. Invalid column name 'IsGroup'
Diagnoses
The archiving database must have been a little old and it did not appear to have the "Identity" and "IsGroup" columns.
Resolution
Creating a new archiving database seems to have done the trick. We assume that the archiving DB must have been created in an earlier build where the "Identity" and "IsGroup" columns were not implemented yet.