<<I am using firebirdsql with JDBC, me process has to add messages
constantly to the database, but somehow at some point the connection
with the database is lost and messaged don't get added in the database.>>

When posting problems, define what versions of software you are using...
Firebird Version? JayBird version?

<snip>

<<Does someone know what this is? And how I can fix this?>>

Posting the problem to the JayBird
list rather than the generic support list might get you a faster answer.
Does the latest beta version of the driver fix the problem?
Does the latest version of the source fix the problem?

Regards
Paul