Database corruption....

  Hello,
I have problem with my database - there is a table, called stats, which
isn't working... The problem looks like this:
www=> select count(login) from stats;
ERROR:  cannot read block 839 of stats
FATAL 1:  Memory exhausted in AllocSetAlloc()
pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally
        before or while processing the request.
We have lost the connection to the backend, so further processing is
impossible.  Terminating.

 And I had this error, too:
FATAL: s_lock(401d2004) at bufmgr.c:1106, stuck spinlock. Aborting.
NOTICE:  Message from PostgreSQL backend:
        The Postmaster has informed me that some other backend died
abnormally and possibly corrupted shared memory.
        I have rolled back the current transaction and am going to
terminate your database system connection and exit.
        Please reconnect to the database system and repeat your query.

Somebody got a clue what can I do ? There is a chapter in the manual about
recovery, but looks like there weren't any volunteers to write it...
I'm using postgresql-6.5.3 from Debian 2.2 potato.

p.s. this is somehow urgent :) If there is quick and dirty fix, it will
be great :)