Postgres superuser priviledges

Hi
I am new to Postgres. I am trying to load a C function in Postgres under
Red Hat Linux.
I compile using
 gcc -I$PGROOT -I$PGROOT/include -I$PGROOT/src/include -c phone.c
to produce the object file 'phone.o'
Then I link using
 ld -Bdynamic -o phone.so phone.o -lc
to produce the shared object 'phone.so'.
(Assuming I am doing things right so far) Then from psql:

 =>  CREATE FUNCTION phone_in(opaque)
     RETURNS phone
      AS '/home/M97/acs/vassilik/protein/phone.so'
     LANGUAGE 'c';
 NOTICE:  ProcedureCreate: type 'phone' is not yet defined
 CREATE

Same for the output function, the type itself and a table that uses the
type.
Then
 test=> INSERT INTO test_phone VALUES ('01483-827294','0161-2242394');
 PQexec() -- Request was sent to backend, but backend closed the channel
before responding.
        This probably means the backend terminated abnormally before or
while processing the request.

Why???????????????????
Initially, I thought it's because I did not have superuser priviledges.
However, if I didn't I would not be able to issue CREATE FUNCTION for a C
function ( I had this problem in the past and I had the system
administrator change my entry in the pg_user table so that the attribute
'usesuper' is set to true).

I get the same message from PQexec() when typing
  test=> load '/home/M97/acs/vassilik/protein/phone.so';


I think there is something wrong with the flags I used during compilation
or linkediting (I even tried to create a Makefile as somebody suggested to
me but I still had the same problems)

Can somebody help me? Anybody used Postgres under Linux Red Hat before?
I really need to know because I am stuck at this and cannot proceed with
my project.
Kostas