DISTINCT is not quite distinct

I run this innocent query

CREATE TABLE foo AS SELECT DISTINCT bar FROM baz ORDER BY bar;

and the resulting table contains duplicate rows. 8-(

According to EXPLAIN, an index scan on the bar column is used (using
the underlying B-tree index).  This is with PostgreSQL 8.1.4 (Debian
package 8.1.4-6).  Is this a known problem?

If I drop the DISTINCT, the output is not correctly ordered, either.
Perhaps this is an index corruption issue?  The hardware itself seems
fine.

--
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99