The connection to the external data source could not be established. No SDBC driver was found for the URL ‘sdbc:embedded:hsqldb’.
What are the circumstances of the error? Perhaps a Writer document is trying to connect to a database but the database is not registered (in Tools-Options-Base-Databases).
Also, as this error can be related to a number of items, the database being used (ie: HSQL, Access, Firebird, etc), the OS, the LO version, and whether it is 32 or 64 bit LO is important. Please provide.