FYI for everyone: the customer contacted us via email. Screenshots of Configuration/Scanning Setup/Database Scripts and the customer's error log indicated that the event log database tables were huge and locking up the Compact database. Clearing event log data resolved the issue.
If you have over 1,000 assets, it is recommended that you use SQL Server as your database server, not SQL Compact. Performance will be severely impacted if you try to host thousands of assets in a Compact database. Instructions for moving from SQL Compact to SQL Server can be found
here.