libkrb5 has issues working in processes that have more than 1024 files open due to the use of select() Upstream has a patch to make libkrb5 use poll() instead. Please backport it to RHEL5 so that daemons like samba do not have issues in those cases.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2012-0306.html