> It seems I run into timeout problems with JBoss and pooled firebird connection. But as I am pretty new to JBoss, Firebird and Java, I haven't got a clue what to do about it.
>
> In case of the error below I have to restart JBoss to get rid of the problem. The problem then re-arises after a few minutes (of inactivity?).
>
> Any idea?

IIRC, it can happen only when the application tries to close the already
closed connection. Do you call XAConnection.close() method in your code?

Roman