tsearch2,pgsql 7.4.[1|2], pg_dump problem

Hi, i noticed a failure when i pg_dump/reload a database with tsearch2.sql
installed.

I get ERRORS of the type:

dynacom=# SELECT lexize('en_stem','foo bar');
ERROR: cache lookup failed for function 4652394
dynacom=# SELECT lexize('en_stem','foo bar');
ERROR: cache lookup failed for function 4652394
dynacom=# SELECT lexize('en_stem','foo bar');
ERROR: cache lookup failed for function 4652394
dynacom=# SELECT lexize('en_stem','foo bar');
ERROR: cache lookup failed for function 4652394
dynacom=#
dynacom=# SELECT to_tsvector('default','foo bar');
ERROR: cache lookup failed for function 4652424
dynacom=# SELECT to_tsvector('default','foo bar');
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>
!>
!> \q

Always the 1st call in a session to to_tsvector gives:
ERROR: cache lookup failed for function 4652424
and the very next call in the same session causes the postmaster
to SEGV.

This situation is demonstrated in FreeBSD 5.1-RELEASE-p10, pgsql 7.4.1
and in Debian 2.4.18-bf2.4, pgsql 7.4.2.

A workaround is to first load tsearch2.sql script in the newly created
database, reload the dump, and ignore any tsearch2 subsequent ERRORS.

Anyone has a clue?

--
-Achilleus