Postgres crashes,help to recover

I have Postgres 8 running on Windows XP
The size of data subdirectory is 326 MB

Today morning suddenly one table in one database, firma1.klient is
corrupted. When trying to backup it using pgAdmin III I get the log below
and backup is not created.

I have:

1. Compressed backup of the whole database as of 15.7
2. Compressed backup of the firma1 schema of this database as of 19.7 where
corrupted table klient resides.

How to get the database back working by repairing firma1.klient table or by
restoring this from schema backup.
Why Postgres crashes ? I use default postgres.conf file which has probably
fsync on

Log when trying to backup table:

.....
pg_dump: restoring data for table "klient"
pg_dump: dumping contents of table klient
pg_dump: ERROR: out of memory
DETAIL: Failed on request of size 544565107.
pg_dump: SQL command to dump the contents of table "klient" failed:
PQendcopy() failed.
pg_dump: Error message from server: ERROR: out of memory
DETAIL: Failed on request of size 544565107.
pg_dump: The command was: COPY firma1.klient (kood, nimi, a_a, p_kood,
regnr, vatpayno, piirkond, postiindek, tanav, kontaktisi, telefon, faks,
email, wwwpage, liik, viitenr, riik, riik2, riigikood, hinnak, erihinnak,
myygikood, objekt2, objekt5, objekt7, maksetin, omakseti, krediit,
ostukredii, masin, info, maksja, "timestamp", atimestamp, elanikud, pindala,
grmaja, apindala, kpindala, idmakett, tulemus, omandisuhe, username,
changedby, parool, hinnaale, mitteakt, kontakteer, klikaart, mhprotsent,
aadress, grupp, verskp, firma_enne, tegevusala, instkuupae, firmarv,
tookohti, versioon, teenlepkp, jur, kasutab, est, rus, miniest, minirus,
plakat, keel) TO stdout;
pg_dump: *** aborted because of error

Process returned exit code 1.