When I returned to the project on Friday I found that the Information Store service refused to start. The Event Viewer showed:
Event ID: 301
During the original work on the machine, I'd installed an eval of Forefront Server Protection. That eval is long-since expired.Failed to mount database 'Mailbox Database 0696636359' on Exch2010.jacobshome.local (Duration=00:00:00.3719227, ErrorMessage=An Active Manager operation failed with a transient error. Please retry the operation. Error: A transient error occurred during discovery of the database availability group topology. Error: Database action failed with transient error. Error: A transient error occurred during a database operation. Error: MapiExceptionNetworkError: Unable to make admin interface connection to server. (hr=0x80040115, ec=-2147221227)
I uninstalled the Forefront Protection (no reboot was necessary), and the IS service started right up, no muss, no fuss.
Hope this helps somebody.