major flaw in 6.5beta1??? (UPDATE/INSERT waiting)

Hi,

I'm quite shocked, I hope this is dream:

> psql cs
Welcome to the POSTGRESQL interactive sql monitor:
  Please read the file COPYRIGHT for copyright terms of POSTGRESQL
[PostgreSQL 6.5.0 on i686-pc-linux-gnu, compiled by gcc egcs-2.91.5]

   type \? for help on slash commands
   type \q to quit
   type \g or terminate with semicolon to execute query
 You are currently connected to the database: cs


cs=> select envelope from recipient where envelope=510349;
envelope
--------
   88320
  510349
  510349
  510349
  510349
  510349
  510349
  510349
  510349
  510349
  510349
  510349
(12 rows)

To my understanding the first should have been *never* selected. 

I had a strange problem tonight, where the backends stopped working
saying something like this

UPDATE waiting
INSERT waiting

dead locks? how can these happen? killed some backends, and restarted
the server. Seems part of the db are corrupted now. Back to 6.4.2?

Dirk