PG 9.0.1 database errors

Hello Gurus,
One of our Pg ver 9.0.1 on RHES 5-64 bits server crashed this
weekend, we restarted the db and start seeing the following error, we
can't see any disks error in OS error log related to this crashed, no
software changes to the system so far
I would like to get more info about the error and what's the workaround
to fix the issue:

ERROR:
invalid byte sequence for encoding "UTF8": 0xff
2011-07-25 07:23:45 PDT[23250]:[2-1]STATEMENT: COPY irod.r_data_main
(data_id, coll_id, data_name, data_repl_num, data_version,
data_type_name, data_size, resc_group_name, resc_name, data_path,
data_owner_name, data_owner_zone, data_is_dirty, data_status,
data_checksum, data_expiry_ts, data_map_id, data_mode, r_comment,
create_ts, modify_ts) TO stdout;
2011-07-25 07:26:05 PDT[31080]:[1-1]LOG: incomplete startup packet
2011-07-25 07:27:24 PDT[935]:[1-1]ERROR: invalid page header in block
5665176 of relation pg_tblspc/16390/PG_9.0_201008051/16393/16453
2011-07-25 07:27:24 PDT[935]:[2-1]CONTEXT: automatic vacuum of table
"ICAT.irod.r_data_main"
Thank you
Isabella

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Isabella A. Ghiurea

Isabella(dot)Ghiurea(at)nrc-cnrc(dot)gc(dot)ca
Canadian Astronomy Data Centre |http://www.nrc-cnrc.gc.ca/eng/services/hia/data-centre.html
National Research Council of Canada, Herzberg Institute of Astrophysics
5071 West Saanich Road, Victoria BC V9E 2E7, Canada
Phone: 250 363-3446 fax: 250 363-0045