failed to re-find parent key in index "22723655" for split pages 370836/370837

Hello
I am facing problems starting the database. Following is the error message.
Can anyone help me?

Parameters

synchronous_commit = off
archive_mode = on
sync = on

Postgres 8.4.5
Linux 2.6.18-194.3.1.el5 # 1 SMP Thu May 13 13:08:30 EDT 2010 x86_64 x86_64
x86_64 GNU / Linux
2010-11-29 18:12:20 BRST [] - [5011]: [1-1] LOG: 00000: database system was
interrupted while in recovery at 2010-11-29 18:09:31 BRST
2010-11-29 18:12:20 BRST [] - [5011]: [2-1] HINT: This probably means that
some data is corrupted and you will have to use the last backup for
recovery.
2010-11-29 18:12:20 BRST [] - [5011]: [3-1] LOCATION: StartupXLOG,
xlog.c:5265
2010-11-29 18:12:20 BRST [] - [5011]: [4-1] LOG: 00000: database system was
not properly shut down; automatic recovery in progress
2010-11-29 18:12:20 BRST [] - [5011]: [5-1] LOCATION: StartupXLOG,
xlog.c:5449
2010-11-29 18:12:20 BRST [] - [5011]: [6-1] LOG: 00000: redo starts at
270/55E04AE8
2010-11-29 18:12:20 BRST [] - [5011]: [7-1] LOCATION: StartupXLOG,
xlog.c:5532
2010-11-29 18:12:41 BRST [] - [5011]: [8-1] LOG: 58P01: could not open file
"pg_xlog/0000000100000270000000CC" (log file 624, segment 204): No such file
or directory
2010-11-29 18:12:41 BRST [] - [5011]: [9-1] LOCATION: XLogFileRead,
xlog.c:2600
2010-11-29 18:12:41 BRST [] - [5011]: [10-1] LOG: 00000: redo done at
270/CBFFE940
2010-11-29 18:12:41 BRST [] - [5011]: [11-1] LOCATION: StartupXLOG,
xlog.c:5664
2010-11-29 18:12:41 BRST [] - [5011]: [12-1] LOG: 00000: last completed
transaction was at log time 2010-11-26 01:55:01.259996-02
2010-11-29 18:12:41 BRST [] - [5011]: [13-1] LOCATION: StartupXLOG,
xlog.c:5668
2010-11-29 18:12:41 BRST [] - [5011]: [14-1] FATAL: XX000: failed to
re-find parent key in index "22723655" for split pages 370836/370837
2010-11-29 18:12:41 BRST [] - [5011]: [15-1] LOCATION: _bt_insert_parent,
nbtinsert.c:1578
2010-11-29 18:12:41 BRST [] - [5009]: [1-1] LOG: 00000: startup process
(PID 5011) exited with exit code 1
2010-11-29 18:12:41 BRST [] - [5009]: [2-1] LOCATION: LogChildExit,
postmaster.c:2720
2010-11-29 18:12:41 BRST [] - [5009]: [3-1] LOG: 00000: aborting startup
due to startup process failure
2010-11-29 18:12:41 BRST [] - [5009]: [4-1] LOCATION: reaper,
postmaster.c:2261