pg 7.3.4 and linux box crash

Hi,
I am runing linux red hat 7.3 (standart install)
on dual athlon box , 1 GB ram and pg 7.3.4.

If I try to access with pgAdmin one from my tables (i contains ~ 1 M
records)
the linux box crashes.
In my pg log I can find:
ERROR: Invalid page header in block 5604 of a_acc

before this error I see also :
FATAL: Database "template0" is not currently accepting connections
ERROR: Relation "pg_relcheck" does not exist

and

ERROR: 'ksqo' is not a valid option name

I am using reiserFS on this box and do not find any other problems with
it.

Can I solve this problem or I need to recreate the datebase ( The table
and the database are created befor 2 days)?

regards,
ivan.