server closed the connection unexpectedly

Dear all,

i'm unable to connect postgres server with error :

C:\Program Files\PostgreSQL\8.2\bin>psql -U postgres siakad
Password for user postgres:
psql: server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.

pg_log :

2007-08-19 03:00:50 LOG: database system was shut down at 2007-08-19 02:58:26 Malay Peninsula Standard Time
2007-08-19 03:00:50 LOG: checkpoint record is at 0/75A808
2007-08-19 03:00:50 LOG: redo record is at 0/75A808; undo record is at 0/0; shutdown TRUE
2007-08-19 03:00:50 LOG: next transaction ID: 0/1931; next OID: 16737
2007-08-19 03:00:50 LOG: next MultiXactId: 1; next MultiXactOffset: 0
2007-08-19 03:00:51 LOG: database system is ready
2007-08-19 03:01:43 LOG: could not receive data from client: An operation was attempted on something that is not a socket.

2007-08-19 03:01:43 LOG: incomplete startup packet

somebody help me please