I think you need to explain more with special reference to:

> This exception occurs if I try and open 2 datasets sequentially
> on the same Firebird database.
>
> The queries are all connected through a TDatabase object to the
> same Firebird database via ODBC. The same code works fine against MSSQL.
>

1. 2 datasets Vs all queries
2. TDatabase via ODBC - how do you make this happen? Is this TDatabase of
IBX components? in Delphi? in C++Builder?
3. What ODBC driver?
4. TDatabase does not need ODBC - so ?????

Alan