Here's the followup on what happenned... I forgot to mention that PostgreSQL only became this unstable immediately AFTER I reloaded my database from a pg_dump. I had been running it with different -B and -o flags fro a couple hours already.

Interesting thing is that even with AOLserver down, going to psql and trying to delete a row from a table would cause the backend to die. So it had nothing to do with AOLserver.

So after wandering for a while, I dropdb'd and reloaded my database from scratch from the openacs datamodel... Voila ! No more instabilities... PostgreSQL has been working like a charm.

Could this mean that there's a problem with pg_dump ?