If you have a RHEL6.1 and try to update to RHEL6.4, you will get some strange errors, about missing libraries.
The reason is that ldconfig will not run anymore, because /etc/ld.so.conf.d/kernel-2.6.32-* sepcifies hwcap 0 till RHEL6.1 and RHEL 6.2 and higher specifies hwcap 1.
It the settings are different you get this error message:
ldconfig: /etc/ld.so.conf.d/kernel-2.6.32-71.29.1.el6.x86_64.conf:6: hwcap index 1 already defined as nosegneg
ldconfig cannot run after installing new libraries and some symlinks are broken.
To Fix: simply change all hwcap setting to 1 and rerun ldconfig.