VACUUM causes violent postmaster death

Server process (pid 13361) exited with status 26 at Fri Nov 3 17:49:44 2000
Terminating any active server processes...
NOTICE: Message from PostgreSQL backend:
The Postmaster has informed me that some other backend died abnormally and possibly corrupted shared memory.
I have rolled back the current transaction and am going to terminate your database system connection and exit.
Please reconnect to the database system and repeat your query.

This happens fairly regularly. I assume exit code 26 is used to dictate
that a specific error has occured.

The database is a decent size (~3M records) with about 4 indexes.

-Dan
--
Man is a rational animal who always loses his temper when he is called
upon to act in accordance with the dictates of reason.
-- Oscar Wilde