postgre restarts in short period

Hi,

Our client has began to complain for a few days that the application can
not connect to the database more times.
I looked into the logs and as far as I can see, postgresql restarts more
times a day. I made a vacuum (full, freeze, analyze) on the database and
reindexed everything, but it looks, nothing has changed.

Server data:
Windows Standard Server 2007 SP2 64 bit
Intel Xeon 3GHz
4MB ram

Postgresql 8.2 32 bit

The application is writen in php.

I paste here the logs for one day:

postgresql-2013-08-05_044313.log:
2013-08-05 04:43:13 FATAL: the database system is starting up
2013-08-05 04:43:13 LOG: database system was interrupted at 2013-08-04
21:17:08
2013-08-05 04:43:13 LOG: checkpoint record is at A/C07BA3D0
2013-08-05 04:43:13 LOG: redo record is at A/C07BA3D0; undo record is
at 0/0; shutdown TRUE
2013-08-05 04:43:13 LOG: next transaction ID: 0/86886248; next OID:
28623177
2013-08-05 04:43:13 LOG: next MultiXactId: 88; next MultiXactOffset: 175
2013-08-05 04:43:13 LOG: database system was not properly shut down;
automatic recovery in progress
2013-08-05 04:43:14 LOG: record with zero length at A/C07BA420
2013-08-05 04:43:14 LOG: redo is not required
2013-08-05 04:43:14 FATAL: the database system is starting up
2013-08-05 04:43:14 LOG: database system is ready
2013-08-05 04:43:24 LOG: could not receive data from client: Unknown
winsock error 10061
2013-08-05 04:43:24 LOG: unexpected EOF on client connection

postgresql-2013-08-05_063316.log:
2013-08-05 06:33:17 FATAL: the database system is starting up
2013-08-05 06:33:17 LOG: database system was interrupted at 2013-08-05
04:43:14
2013-08-05 06:33:17 LOG: checkpoint record is at A/C07BA420
2013-08-05 06:33:17 LOG: redo record is at A/C07BA420; undo record is
at 0/0; shutdown TRUE
2013-08-05 06:33:17 LOG: next transaction ID: 0/86886248; next OID:
28623177
2013-08-05 06:33:17 LOG: next MultiXactId: 88; next MultiXactOffset: 175
2013-08-05 06:33:17 LOG: database system was not properly shut down;
automatic recovery in progress
2013-08-05 06:33:17 LOG: record with zero length at A/C07BA470
2013-08-05 06:33:17 LOG: redo is not required
2013-08-05 06:33:18 FATAL: the database system is starting up
2013-08-05 06:33:18 LOG: database system is ready
2013-08-05 06:33:19 FATAL: the database system is starting up

postgresql-2013-08-05_084852.log:
2013-08-05 08:48:53 LOG: database system was interrupted at 2013-08-05
08:43:19
2013-08-05 08:48:53 FATAL: the database system is starting up
2013-08-05 08:48:53 LOG: checkpoint record is at A/C0940F58
2013-08-05 08:48:53 LOG: redo record is at A/C0940F58; undo record is
at 0/0; shutdown FALSE
2013-08-05 08:48:53 LOG: next transaction ID: 0/86889158; next OID:
28631369
2013-08-05 08:48:53 LOG: next MultiXactId: 88; next MultiXactOffset: 175
2013-08-05 08:48:53 LOG: database system was not properly shut down;
automatic recovery in progress
2013-08-05 08:48:54 FATAL: the database system is starting up
2013-08-05 08:48:54 LOG: redo starts at A/C0940FA8
2013-08-05 08:48:54 FATAL: the database system is starting up
2013-08-05 08:48:54 FATAL: the database system is starting up
2013-08-05 08:48:54 FATAL: the database system is starting up
2013-08-05 08:48:55 FATAL: the database system is starting up
2013-08-05 08:48:56 FATAL: the database system is starting up
2013-08-05 08:48:57 FATAL: the database system is starting up
2013-08-05 08:48:59 FATAL: the database system is starting up
2013-08-05 08:49:00 FATAL: the database system is starting up
2013-08-05 08:49:01 FATAL: the database system is starting up
2013-08-05 08:49:02 FATAL: the database system is starting up
2013-08-05 08:49:03 FATAL: the database system is starting up
2013-08-05 08:49:04 FATAL: the database system is starting up
2013-08-05 08:49:05 FATAL: the database system is starting up
2013-08-05 08:49:06 FATAL: the database system is starting up
2013-08-05 08:49:07 FATAL: the database system is starting up
2013-08-05 08:49:08 FATAL: the database system is starting up
2013-08-05 08:49:09 FATAL: the database system is starting up
2013-08-05 08:49:11 FATAL: the database system is starting up
2013-08-05 08:49:11 LOG: record with zero length at A/C096B8B0
2013-08-05 08:49:11 LOG: redo done at A/C096B880
2013-08-05 08:49:12 FATAL: the database system is starting up
2013-08-05 08:49:13 FATAL: the database system is starting up
2013-08-05 08:49:14 FATAL: the database system is starting up
2013-08-05 08:49:15 FATAL: the database system is starting up
2013-08-05 08:49:16 FATAL: the database system is starting up
2013-08-05 08:49:16 LOG: database system is ready
2013-08-05 08:49:18 FATAL: the database system is starting up
2013-08-05 10:18:01 ERROR: syntax error at or near "and" at character 195
2013-08-05 10:18:01 STATEMENT: select distinct count(*) as rownum from
minta as m join partner as p on ( m.partnerid = p.partnerid ) join
mintajelleg as mj on ( mj.mintajellegid = m.mintajellegid ) where
m.status IN and m.mintajellegid = and m.partnerid =

postgresql-2013-08-05_155425.log:
2013-08-05 15:54:26 FATAL: the database system is starting up
2013-08-05 15:54:26 LOG: database system was interrupted at 2013-08-05
15:49:18
2013-08-05 15:54:26 LOG: checkpoint record is at A/C352B138
2013-08-05 15:54:26 LOG: redo record is at A/C352B138; undo record is
at 0/0; shutdown FALSE
2013-08-05 15:54:26 LOG: next transaction ID: 0/86971106; next OID:
28647753
2013-08-05 15:54:26 LOG: next MultiXactId: 88; next MultiXactOffset: 175
2013-08-05 15:54:26 LOG: database system was not properly shut down;
automatic recovery in progress
2013-08-05 15:54:27 LOG: redo starts at A/C352B188
2013-08-05 15:54:27 FATAL: the database system is starting up
2013-08-05 15:54:28 LOG: record with zero length at A/C3538F90
2013-08-05 15:54:28 LOG: redo done at A/C3538F60
2013-08-05 15:54:28 FATAL: the database system is starting up
2013-08-05 15:54:29 FATAL: the database system is starting up
2013-08-05 15:54:30 LOG: database system is ready
2013-08-05 15:54:30 FATAL: the database system is starting up
2013-08-05 15:54:38 LOG: unexpected EOF on client connection

I hope somebody has an idea how I can correct it.
Thanks for the help!

fenor