Database shut down unexpectedly.

Today the database shut down unexpectedly. I have included the log file
that shows the shutdown. Can anybody tell me why this happened and how I can
make sure it doesn't happen again.

The only thing I can think of that I did was to specify a password for the
postgres user in the operating system.

Here is the log file. Very strange.

2009-03-25 00:02:01 GMT LOG: incomplete startup packet
2009-03-25 00:30:05 GMT LOG: could not receive data from client: Connection
timed out
2009-03-25 00:30:05 GMT LOG: unexpected EOF on client connection
2009-03-25 00:30:05 GMT LOG: could not receive data from client: Connection
timed out
2009-03-25 00:30:05 GMT LOG: unexpected EOF on client connection
2009-03-25 00:32:15 GMT LOG: could not receive data from client: Connection
timed out
2009-03-25 00:32:15 GMT LOG: unexpected EOF on client connection
2009-03-25 02:41:57 GMT LOG: incomplete startup packet
2009-03-25 02:41:57 GMT LOG: received smart shutdown request
2009-03-25 02:41:57 GMT LOG: autovacuum launcher shutting down
2009-03-25 02:45:03 GMT FATAL: the database system is shutting down
2009-03-25 02:45:03 GMT FATAL: the database system is shutting down
2009-03-25 02:50:02 GMT FATAL: the database system is shutting down
2009-03-25 02:50:02 GMT FATAL: the database system is shutting down
2009-03-25 02:55:03 GMT FATAL: the database system is shutting down
2009-03-25 02:55:03 GMT FATAL: the database system is shutting down
2009-03-25 03:00:03 GMT FATAL: the database system is shutting down
2009-03-25 03:00:03 GMT FATAL: the database system is shutting down
2009-03-25 03:05:03 GMT FATAL: the database system is shutting down
2009-03-25 03:05:03 GMT FATAL: the database system is shutting down
2009-03-25 03:10:02 GMT FATAL: the database system is shutting down
2009-03-25 03:10:02 GMT FATAL: the database system is shutting down
2009-03-25 03:15:03 GMT FATAL: the database system is shutting down
2009-03-25 03:15:03 GMT FATAL: the database system is shutting down
2009-03-25 03:20:03 GMT FATAL: the database system is shutting down
2009-03-25 03:20:03 GMT FATAL: the database system is shutting down
2009-03-25 03:25:02 GMT FATAL: the database system is shutting down
2009-03-25 03:25:02 GMT FATAL: the database system is shutting down
2009-03-25 03:30:03 GMT FATAL: the database system is shutting down
2009-03-25 03:30:03 GMT FATAL: the database system is shutting down
2009-03-25 03:35:03 GMT FATAL: the database system is shutting down
2009-03-25 03:35:03 GMT FATAL: the database system is shutting down
2009-03-25 03:40:02 GMT FATAL: the database system is shutting down
2009-03-25 03:40:02 GMT FATAL: the database system is shutting down
2009-03-25 03:45:02 GMT FATAL: the database system is shutting down
2009-03-25 03:45:02 GMT FATAL: the database system is shutting down
2009-03-25 03:50:03 GMT FATAL: the database system is shutting down
2009-03-25 03:50:03 GMT FATAL: the database system is shutting down
2009-03-25 03:55:03 GMT FATAL: the database system is shutting down
2009-03-25 03:55:03 GMT FATAL: the database system is shutting down
2009-03-25 04:00:02 GMT FATAL: the database system is shutting down
2009-03-25 04:00:02 GMT FATAL: the database system is shutting down
2009-03-25 04:25:03 GMT FATAL: the database system is shutting down
2009-03-25 04:30:03 GMT FATAL: the database system is shutting down
2009-03-25 04:30:03 GMT FATAL: the database system is shutting down
2009-03-25 04:35:02 GMT FATAL: the database system is shutting down
2009-03-25 04:35:02 GMT FATAL: the database system is shutting down
2009-03-25 04:40:03 GMT FATAL: the database system is shutting down
2009-03-25 04:40:03 GMT FATAL: the database system is shutting down
2009-03-25 04:45:03 GMT FATAL: the database system is shutting down
2009-03-25 04:45:03 GMT FATAL: the database system is shutting down
2009-03-25 04:50:02 GMT FATAL: the database system is shutting down
2009-03-25 04:50:02 GMT FATAL: the database system is shutting down
2009-03-25 04:55:03 GMT FATAL: the database system is shutting down
2009-03-25 04:55:03 GMT FATAL: the database system is shutting down
2009-03-25 05:00:03 GMT FATAL: the database system is shutting down
2009-03-25 05:00:03 GMT FATAL: the database system is shutting down
2009-03-25 05:02:01 GMT LOG: incomplete startup packet
2009-03-25 05:05:02 GMT FATAL: the database system is shutting down
2009-03-25 05:05:02 GMT FATAL: the database system is shutting down
2009-03-25 05:10:02 GMT FATAL: the database system is shutting down
2009-03-25 05:10:02 GMT FATAL: the database system is shutting down
2009-03-25 05:15:03 GMT FATAL: the database system is shutting down
2009-03-25 05:15:03 GMT FATAL: the database system is shutting down
2009-03-25 05:20:03 GMT FATAL: the database system is shutting down
2009-03-25 05:20:03 GMT FATAL: the database system is shutting down
2009-03-25 05:25:02 GMT FATAL: the database system is shutting down
2009-03-25 05:25:02 GMT FATAL: the database system is shutting down
2009-03-25 05:30:03 GMT FATAL: the database system is shutting down
2009-03-25 05:30:03 GMT FATAL: the database system is shutting down
2009-03-25 05:35:03 GMT FATAL: the database system is shutting down
2009-03-25 05:35:03 GMT FATAL: the database system is shutting down
2009-03-25 05:40:02 GMT FATAL: the database system is shutting down
2009-03-25 05:40:02 GMT FATAL: the database system is shutting down
2009-03-25 05:45:02 GMT FATAL: the database system is shutting down
2009-03-25 05:45:02 GMT FATAL: the database system is shutting down
2009-03-25 05:50:03 GMT FATAL: the database system is shutting down
2009-03-25 05:50:03 GMT FATAL: the database system is shutting down
2009-03-25 05:55:03 GMT FATAL: the database system is shutting down
2009-03-25 05:55:03 GMT FATAL: the database system is shutting down
2009-03-25 06:00:02 GMT FATAL: the database system is shutting down
2009-03-25 06:00:02 GMT FATAL: the database system is shutting down
2009-03-25 06:05:03 GMT FATAL: the database system is shutting down
2009-03-25 06:05:03 GMT FATAL: the database system is shutting down
2009-03-25 06:10:03 GMT FATAL: the database system is shutting down
2009-03-25 06:10:03 GMT FATAL: the database system is shutting down
2009-03-25 06:15:02 GMT FATAL: the database system is shutting down
2009-03-25 06:15:02 GMT FATAL: the database system is shutting down
2009-03-25 06:20:03 GMT FATAL: the database system is shutting down
2009-03-25 06:20:03 GMT FATAL: the database system is shutting down
2009-03-25 06:25:03 GMT FATAL: the database system is shutting down
2009-03-25 06:25:03 GMT FATAL: the database system is shutting down
2009-03-25 06:30:03 GMT FATAL: the database system is shutting down
2009-03-25 06:30:03 GMT FATAL: the database system is shutting down
2009-03-25 06:35:02 GMT FATAL: the database system is shutting down
2009-03-25 06:35:02 GMT FATAL: the database system is shutting down
2009-03-25 06:40:03 GMT FATAL: the database system is shutting down
2009-03-25 06:40:03 GMT FATAL: the database system is shutting down
2009-03-25 06:45:03 GMT FATAL: the database system is shutting down
2009-03-25 06:45:03 GMT FATAL: the database system is shutting down
2009-03-25 06:50:02 GMT FATAL: the database system is shutting down
2009-03-25 06:50:02 GMT FATAL: the database system is shutting down
2009-03-25 06:55:03 GMT FATAL: the database system is shutting down
2009-03-25 06:55:03 GMT FATAL: the database system is shutting down
2009-03-25 07:00:03 GMT FATAL: the database system is shutting down
2009-03-25 07:00:03 GMT FATAL: the database system is shutting down
2009-03-25 07:05:03 GMT FATAL: the database system is shutting down
2009-03-25 07:05:03 GMT FATAL: the database system is shutting down
2009-03-25 07:06:42 GMT LOG: could not receive data from client: Connection
reset by peer
2009-03-25 07:06:42 GMT LOG: unexpected EOF on client connection
2009-03-25 07:06:42 GMT LOG: shutting down
2009-03-25 07:06:42 GMT LOG: database system is shut down
2009-03-25 08:54:47 GMT LOG: could not load root certificate file
"root.crt": no SSL error reported
2009-03-25 08:54:47 GMT DETAIL: Will not verify client certificates.
2009-03-25 08:54:47 GMT LOG: database system was shut down at 2009-03-25
07:06:42 GMT
2009-03-25 08:54:47 GMT LOG: autovacuum launcher started
2009-03-25 08:54:47 GMT LOG: database system is ready to accept connections
2009-03-25 08:54:48 GMT LOG: incomplete startup packet