Problems of connexion with Tsearch2 functions

I am a beginner with Postgresql and Full-Text indexing enabled by Tsearch2.
I have recently set all the configuration to run Tsearch2 on my
databases (Postgresql 8.2), under Linux (Fedora).
Everything worked great for a period of time. The queries I frequently
used were :
- select finddoc('word') - a special query using the function to_tsquery
- select lexize('word')

Then today, all the queries that call a Tsearch2 function,
instanteanously breaks the connection to the base, failing the query of
course.

1) Example when attempting the query from a Xterminal (french version)

# select set_curdict('fr_ispell');
La connexion au serveur a été coupée à l'improviste
Le serveur s'est peut-être arrêté anormalement
avant ou durant le traitement de la requête.
La connexion au serveur a été perdue. Tentative de réinitialisation : Echec.

2) Example when attempting from our JAVA Application (english version)

# The backend has broken the connection. Possibly the action you have
attempted has caused it to close.
at org.postgresql.PG_Stream.ReceiveChar(PG_Stream.java:140)
at
org.postgresql.core.QueryExecutor.execute(QueryExecutor.java:76) at
org.postgresql.jdbc1.AbstractJdbc1Connection.ExecSQL(AbstractJdbc1Connection.java:505)

at
org.postgresql.jdbc1.AbstractJdbc1Statement.execute(AbstractJdbc1Statement.java:320)
at
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:48)
at
org.postgresql.jdbc1.AbstractJdbc1Statement.executeUpdate(AbstractJdbc1Statement.java:197)
at
org.postgresql.jdbc1.AbstractJdbc1Statement.executeUpdate(AbstractJdbc1Statement.java:183)

Queries like the following work just fine,

# select count(*) from table ;

So what is the problem really ? Anyone experienced something like this
before with Tsearch2 ? Should I reinstall Tsearch2 completely in
Postgresql ? I have already applied 'uninstall_tsearch2.sql' on my base,
but it does not change anything
Thanks you for advise, hope someone can help.
S.G.