weird apt error message

[Guillermo Ontañón <onta@bigfoot.com>]

Hi, the following is an error message thrown by apt when installing a
package.  I don't know how the problem began, because the system is not
mine.  It seems like a perl problem, but we upgraded perl and it keeps
happenning.  I had never seen this error before and I am clueless. Some
of the lines are in Spanish, but those parts are not relevant, I think.
Thanks for your help and sorry if this has already been discussed here.

debconf: Perl may be unconfigured (Can't modify goto in lvalue
subroutine return at /usr/share/perl5/Debconf/Base.pm line 24, near "}"
Compilation failed in require at (eval 4) line 3.
        ...propagated at /usr/share/perl/5.6.1/base.pm line 18.
BEGIN failed--compilation aborted at
/usr/share/perl5/Debconf/Iterator.pm line 5.
Compilation failed in require at /usr/share/perl5/Debconf/Question.pm
line 7.
BEGIN failed--compilation aborted at
/usr/share/perl5/Debconf/Question.pm line 7.
Compilation failed in require at /usr/share/perl5/Debconf/Config.pm line
5.
BEGIN failed--compilation aborted at /usr/share/perl5/Debconf/Config.pm
line 5.
Compilation failed in require at /usr/share/perl5/Debconf/Log.pm line 8.
Compilation failed in require at (eval 1) line 4.
BEGIN failed--compilation aborted at (eval 1) line 4.
) -- aborting
dpkg: error al procesar postgresql (--configure):
el subproceso post-installation script devolvió el código de salida de
error 1
dpkg: problemas de dependencias impiden la configuración de
postgresql-contrib:
postgresql-contrib depende de postgresql (>= 7.1); sin embargo:
  el paquete postgresql no está configurado todavía.
dpkg: error al procesar postgresql-contrib (--configure):
problemas de dependencias - se deja sin configurar
Se encontraron errores al procesar:
postgresql
postgresql-contrib
E: Sub-process /usr/bin/dpkg returned an error code (1)

-- 
Guillermo Ontañón
onta@bigfoot.com
http://mi.barrapunto.com/onta