nope, the forums are all set to "show all" posts. and there's no task manager that i know of in 1.3.1. once again, it isn't simply that posts are disappearing: in the first case there was a discrepancy between what was in the topics table, what was in the posts table and what was in the forum table. not to mention, it is not the oldest posts/topics that are disappearing.
dreamhost says that there should be no problem with the databases at their end--so maybe it is a problem with how invision is writing to the database. tough to say--i was hoping someone might have had a similar experience. doesn't seem to be the case. maybe the time has come to upgrade to a licensed version.