postgres crash when select a record

Hello,
I wish some could help me on this.
I got a table which has 100500 records, when I try to query this particular record
select * from cs_sr_mthly_rtn where mthly_rtn_id = 61609;

Postgres crash, and show this errors:
server closed the connection unexpectedly
 This probably means the server terminated abnormally
 before or while processing the request.
And in the serverlog, it shows:
LOG:  server process (PID 395) was terminated by signal 11
LOG:  terminating any other active server processes
FATAL:  the database system is in recovery mode
LOG:  all server processes terminated; reinitializing
LOG:  database system was interrupted at 2008-05-14 12:52:15 BST
LOG:  checkpoint record is at 0/48DEC034
LOG:  redo record is at 0/48DEC034; undo record is at 0/0; shutdown TRUE
LOG:  next transaction ID: 0/705241; next OID: 49152
LOG:  next MultiXactId: 1; next MultiXactOffset: 0
LOG:  database system was not properly shut down; automatic recovery in progress
LOG:  redo starts at 0/48DEC07C
LOG:  unexpected pageaddr 0/433AC000 in log file 0, segment 74, offset 3850240
LOG:  redo done at 0/4A3ABFC0
LOG:  database system is ready
Because of this, I'm not able to do pg_dump backup anymore.
Anyone can help me to solve this problem?
Thanks
louis