[Zope] Connection problem with database

Hi, If somebody had the same problem as I've now, please let me know something: At certain moments, Zope encounters problems connecting to my database (Interbase, don't know if it is solely Interbase related). When I then Close and reopen the connection, everything works fine again. Somebody experienced this also? Found the error? Or what am I doing wrong? More information on my situation: The database isn't visited often at the moment (only by me). This is just a test-setup. The error happens when there is a long time between 2 requests. As if the connection closes itself, but doesn't opens itself again. Thanks, Tom.