RelationClearRelation: relation X deleted while still in use???

I seem to be getting some bogus "RelationClearRelation: relation
2678605 deleted while still in use" errors. Has anyone seen this
before? This is with only one process running and after a fresh
vacuum. I can fix it by re-running the vacuum and then rerunning
the query. It seems to be random as sometimes but not always I
can simply re-run the query without doing a vacuum and it works
fine the second time.

I'd be happy to hear about a workaround or maybe even a fix.

I have PostgreSQL 7.2.1 running under Solaris 8 on an Intel box.
The database is moderate size, on order 100K rows in some tables.
I can't seem to reproduce the error with anything less then my
full 10K lines of code application.

Here is an Excerpt from my program's log file. It first
prints the error returned from the back end and them prints
the SQL it sent.

ERROR SQL command failed:
ERROR: RelationClearRelation: relation 2678605 deleted while still in
use

ERROR SQL Statment that failed:
select count(location.sequence)
from location, measurement, format, vehicle
where
measurement.name = 'WWB001N' AND
vehicle.project = '401' AND
vehicle.vehicle = '001' AND
vehicle.rev = 'T' AND
format.format_type = 'VEHCENTAUR' AND
location.measurement_id = measurement.measurement_id AND
measurement.format_id = format.format_id AND
format.vehicle_id = vehicle.vehicle_id;

=====
Chris Albertson
Home: 310-376-1029 chrisalbertson90278(at)yahoo(dot)com
Cell: 310-990-7550
Office: 310-336-5189 Christopher(dot)J(dot)Albertson(at)aero(dot)org

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