DBD-Oracle - ORA-24550 signal received

Hi, all
I am using DBD::Oracle 1.23 on an Ubuntu Server 8.04 64 bit system, 
against latest Instant Client:

Client Shared Library 64-bit - 11.2.0.1.0

System name:    Linux
Release:        2.6.9-78.0.0.0.1.ELxenU
Version:        #1 SMP Fri Jul 25 16:25:38 EDT 2008
Machine:        x86_64

with this environment:

LD_LIBRARY_PATH=/usr/lib64/oracle:
TNS_ADMIN=/usr/lib64/oracle/network/admin
PATH=/usr/lib64/oracle:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
PWD=/usr/lib64/oracle
SQLPATH=/usr/lib64/oracle:
DIAGNOSTIC_DEST=/var/log/oracle/adr
ORACLE_HOME=/usr/lib64/oracle

usually the system works well, but about once at week I get this error:

ORA-24550: signal received: [si_signo=11] [si_errno=0] [si_code=1] 
[si_int=80] [si_ptr=0x50] [si_addr=0x624f000]
kpedbg_dmp_stack()+314<-kpeDbgCrash()+166<-kpeDbgSignalHandler()+158<-skgesig_sigactionHandler()+217<-__restore_rt()<-00007FC40C94E2E6Killed

The last time I got this error _after_ my script issued the DBI 
disconnect method, I have no idea about what problem could be, can 
anyone help me?

Thank you in advance for the help you may give,

Anselmo Canfora