I did some more testing and found my first post was inaccurate. It's
the initial connection that's failing. The ODBC error experienced
within my application is "Connectivity error [ODBC Firebird Driver] no
permission for read/select access to Table RDB$RELATIONS." I can
reproduce the problem directly in Windows' ODBC Data Source
Administrator. After I set up a System DSN, with the Database Account
and Password field left blank, a test connection succeeds if I'm
logged in as an administrator, but fails if I'm not, displaying a
brief "Connection to database <database name> failed" error.