You received the output email afterwards?
In my mind we've ruled out:
- common gotchas (incomplete PATH, cron.allow/cron.deny, permissions, etc.)
- dead crond daemon
- selinux
- syntactical problem in, e.g., your /etc/cron.daily scripts
Agree? Unless your system clock is going bonkers, I'm out of ideas for the moment. I do find it interesting that the problem started on one RHEL 5 machine, and then eventually crept into other (CentOS) machines as well.