What could have happened:
- the user's notes.ini isn't or wasn't where it should have been
- the user double-clicked a Notes database in the Explorer
Notes is then started, but not in the Notes data directory where all the other databases are. It starts with the generation of the databases it needs, and one of them is the Workspace database.
Or someone accidentally removed the Workspace, that's also possible.
Otherwise, no clue.
Check for multiple desktop*.* files on the client's PC.