10g database scheduled job does not finish

Hello.
I had one job that was working succesfully but suddenly (no changes in source code or huge data insertions) the job does not finish.
It used to last about 20 min to finish.

This is the info I have gathered:

select * from dba_jobs_running;

       SID        JOB   FAILURES LAST_DATE LAST_SEC THIS_DATE THIS_SEC   INSTANCE
---------- ---------- ---------- --------- -------- --------- -------- ----------
      2057        140          0 13/08/13  04:14:27 26/08/13  13:45:06          2



SQL> select sql_fulltext
  2  from v$sql
  3  where sql_id = '8phdnygh4mpt9';

SQL_FULLTEXT
--------------------------------------------------------------------------------
SELECT /*+ INDEX(a  WF_PK_DET_TRAMITES) */ VALOR FROM WF_DETALLES_TRAMITES A WHE
RE A.ID_TRAMITE = :B5 AND ID_ETAPA_PROCESO = :B4 AND NOMBRE_FUNCION = :B3 AND NO