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