vacuum is failing

I've got a server running PostgreSQL-7.2.3 on RHAS-2.1.  The version
of Postgresql is *not* my choice, I would have gone with something
much more current, but i digress.

Running 'vacuumdb -a -z -v -f' has started failing:

NOTICE:  Index pg_toast_218644531_idx: Pages 1; Tuples 0.
        CPU 0.00s/0.00u sec elapsed 0.00 sec.
NOTICE:  Analyzing doc2_review_comments
NOTICE:  --Relation groups--
NOTICE:  Pages 28: Changed 0, reaped 2, Empty 0, New 0; Tup 331: Vac
2, Keep/VTL 0/0, UnUsed 1, MinLen 160, MaxLen 1988; Re-using:
Free/Avail. Space 13360/12448; EndEmpty/Avail. Pages 0/17.
        CPU 0.01s/0.00u sec elapsed 0.07 sec.
NOTICE:  Index grps: Pages 2; Tuples 331: Deleted 2.
        CPU 0.00s/0.00u sec elapsed 0.00 sec.
NOTICE:  Index groups_public: Pages 2; Tuples 331: Deleted 2.
        CPU 0.00s/0.00u sec elapsed 0.02 sec.
NOTICE:  Index groups_status: Pages 2; Tuples 331: Deleted 2.
        CPU 0.00s/0.00u sec elapsed 0.00 sec.
NOTICE:  Index groups_type: Pages 2; Tuples 331: Deleted 2.
        CPU 0.00s/0.00u sec elapsed 0.00 sec.
NOTICE:  Index group_unix_uniq: Pages 4; Tuples 331: Deleted 2.
        CPU 0.00s/0.00u sec elapsed 0.00 sec.
ERROR:  No one parent tuple was found


Anyone have any suggestions on how to correct this?  This DB serves a
web based PHP application, and right now there isn't any end user
noticable problems, and i'd like to keep it that way :)

thanks in advance!

--
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L. Friedman                                    netllama@gmail.com
LlamaLand                       http://netllama.linux-sxs.org