vacumm error

I'm running postgresql 7.2.1 on linux.

I cannot run vacuumm on a table in a database i'm running for about 7 month=
s.
I get:

ERROR:  No one parent tuple was found

I've found an older posting about that but the poster said that after=20
restarting it was fixed. In my case this is not true. I've restarted=20
postgresql but it didn't work. Noone else is trying to use this database=20
(other databases are used).

test=3D> vacuum full analyze verbose entities;
NOTICE:  --Relation entities--
NOTICE:  Pages 312833: Changed 107130, reaped 273241, Empty 0, New 0; Tup=
=20
9895954: Vac 9005277, Keep/VTL 0/0, UnUsed 44715182, MinLen 36, MaxLen 36;=
=20
Re-using: Free/Avail. Space 1945751280/1945279044; EndEmpty/Avail. Pages=20
0/273480.
        CPU 31.30s/9.81u sec elapsed 138.29 sec.
NOTICE:  Index entities_pkey: Pages 277210; Tuples 9895954: Deleted 9005277.
        CPU 33.33s/75.02u sec elapsed 401.49 sec.
ERROR:  No one parent tuple was found

I had fsync=3Dfalse in postgresql.conf and the machine crashed but i didn't
notice anything strange since then. I've seen the database to grow up each
day after i did a kill -9 to two db backends. At that time postgre restarted
telling me that the shared memory area is possibly corrupted.

The table entities is an one column table (don't ask why :):

test=3D# \d entities
                         Table "entities"
 Column |  Type   |                   Modifiers=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
--------+---------+------------------------------------------------
 id     | integer | not null default nextval('seq_entities'::text)
Primary key: entities_pkey
Triggers: RI_ConstraintTrigger_26872259,
          RI_ConstraintTrigger_26872261,
          RI_ConstraintTrigger_26872268,
          RI_ConstraintTrigger_26872270,
          RI_ConstraintTrigger_26872277,
          RI_ConstraintTrigger_26872279,
          RI_ConstraintTrigger_26872286,
          RI_ConstraintTrigger_26872288,
          RI_ConstraintTrigger_26872295,
          RI_ConstraintTrigger_26872297,
          RI_ConstraintTrigger_26872304,
          RI_ConstraintTrigger_26872306,
          RI_ConstraintTrigger_26872313,
          RI_ConstraintTrigger_26872315,
          RI_ConstraintTrigger_26872323,
          RI_ConstraintTrigger_26872325,
          RI_ConstraintTrigger_26872333,
          RI_ConstraintTrigger_26872335,
          RI_ConstraintTrigger_26872343,
          RI_ConstraintTrigger_26872345,
          RI_ConstraintTrigger_26872353,
          RI_ConstraintTrigger_26872355,
          RI_ConstraintTrigger_26872250,
          RI_ConstraintTrigger_26872252,
          RI_ConstraintTrigger_101919110,
          RI_ConstraintTrigger_101919112

I'm currently running vacumm full on another (larger) table=20
(table entities has 312K pages and this one has 1.3M pages)

TIA

<<V13>>