Cron Job Failure

[Darryl W. DeLao Jr.]

For some reason, one of my servers has decided to stop running all of
its scheduled cron jobs.  The cron jobs are still listed and
configured correctly based on the commands to run, times, etc but none
of them run.  They have been running fine now for well over 6 months. 
The only thing that I can think of as to why they stopped running was
some RedHat updates that I applied last week.  All log files on the
server indiciate that the last time the cron jobs ran was on 4/16,
which is the day I applied the updates.  The problem however gets
better, because I have 4 other servers which are exactly like this one
and they got the updates as well and their cron jobs run just fine. 
Just curious if anyone else is having this problem and what have you
done about it?  Also, how can I get my cron jobs working again?  Do I
have to re-create each one?  Some were there by system default.

Thanks for any help in advance,
Darryl