PLS HELP ASAP - BIG TROUBLE HERE!!!!

Excuse me the hype - It seems that ALL my postgres site went down and
I'm not able to make it work again!!!
I've 6.3.2 here, on a 2.0.31 Slackware Linux box - always worked fine.
Today a query crashed under psql - since there were some loose data
left, I vacuumed and rebooted the system. After that, NOTHING works
anymore - psql die with 'no connection to the backend', linked apps
don't work, postgres complain that user 'postgres' (the site admin
account) doesn't exist in pg_shadow, createdb, destroydb, pg_dump,
they're all dead (they all complain that there is no way to connect to
the DB). I even tried to create a completely new DB from scratch using
initdb --pgdata=somewhereelse, and this too failed with the following
error message
-------------
initdb: using /home/postgres/lib/local1_template1.bki.source as input to
create the template database
.
initdb: using /home/postgres/lib/global1.bki.source as input to create
the global classes.
initdb: using /home/postgres/lib/pg_hba.conf.sample as the host-based
authentication control file.

We are initializing the database system with username postgres
(uid=1000).
This user will own all the files and must also own the server process.

initdb: creating template database in ginolatalla/base/template1
Running: postgres -boot -C -F -Dginolatalla -Q template1
ERROR: cannot read block 0 of pg_variable
ERROR: cannot read block 0 of pg_variable
initdb: could not create template database
initdb: cleaning up by wiping out ginolatalla/base/template1
--------------------------

The only thing that's still alive and kicking is the Postmaster. At
least, it runs without complains, but I'm not sure it's doing its duty,
since I've no means to query it at the moment.

I've checked for locks, tmp files ecc. ecc. and it seems there isn't
anyone around. I 'ipccleaned' the resources, nothing changed.

private reply please!! I'm not subscribed!!
Really TIA for all help - I'm desperate.

Bye all

Fabrizio Ermini