Hi Diego,

> By now, all I can say about it is
> that it occurs in a database intensive thread in wich a bunch of queries
> is performed followed by some inserts. Apparently the error is taking
> place in one of the queries.

Try upgrading to JayBird 2.0.0, the old one had some issues in multithreaded
applications accessing the same connection (though that was more JCA issue),
the new one should work ok now.

Otherwise I have no idea what this can be...

Roman