ERROR: Unable to transform targetlist (internal error)

Hello,

I'm getting a really strange error message : ERROR: Unable to transform
targetlist (internal error) when I do a precise query on my database...

I've two tables : Professeurs and ProfesseursDesComediens

efap=> \d Professeurs
Table = professeurs
+----------------------------------+----------------------------------+-
------+
| Field | Type |
Length|
+----------------------------------+----------------------------------+-
------+
| idprofesseur | int4 not null default nextval ( |
4 |
| nom | varchar() not null |
100 |
| prenom | varchar() |
100 |
+----------------------------------+----------------------------------+-
------+
Index: pk_idprofesseur

efap=> \d ProfesseursDesComediens
Table = professeursdescomediens
+----------------------------------+----------------------------------+-
------+
| Field | Type |
Length|
+----------------------------------+----------------------------------+-
------+
| fk_idcomedien | int4 not null |
4 |
| fk_idprofesseur | int4 not null |
4 |
+----------------------------------+----------------------------------+-
------+
Index: uniqueidprofcomediens

When I do this query :

SELECT Professeurs.IdProfesseur, Professeurs.Nom, Professeurs.Prenom,
EXISTS(SELECT * FROM ProfesseursDesComediens WHERE FK_IdComedien = 713
AND Professeurs.IdProfesseur = ProfesseursDesComediens.FK_IdProfesseur)
FROM Professeurs;

I get this error message : ERROR: Unable to transform targetlist
(internal error)

What does that means exactly ? What is my error ???

Thanks in advance !

PS :I'm working on PostgreSQL 6.5.2 on a Debian linux server.

-------------------------------------------------
Bruno BAGUETTE - bruno(dot)baguette(at)netcourrier(dot)com