Tru Huynh, Thank you for your reply. When I enter uname -a I obtain the following output: Linux localhost.localdomain 2.6.18-194.26.1.el5PAE #1 SMP Tue Nov 9 13:34:42 EST 2010 i686 i686 i386 GNU/Linux. This information indicates we are using x86_32 architecture rather than a x86_64 architecture. Also, when I enter rpm -q glibc glibc-devel, I obtain the following output: glibc-2.5.49.el5_57 glibc-devel-2.5.49.el5-5.7. I think we are using a different architecture compared to your x86_64 architecture. Also , we using a different version of glibc and glibc-devel than the versions listed in your reply. Please tell us whether our Callgrind errors are caused by a libc mismatch and if there is a workaround to this lib mismatch. Thank you.