Upon changing the date to dec 31 1999 using date --set, and waiting for the rollover to jan 1 2000 the crond ran it's jobs as normal. Using date --set again and setting the date back to normal the crond would not run any of it's jobs. The log file for the crond reported nothing. Killing and restarting the daemon left and error in the crond stating that the PID was already in use. None of the crontab files in either /etc/crontab or /var/spool/user were modified when the date was jan 1. The problem was resolved by rebooting the machine.
*** This bug has been marked as a duplicate of 2596 ***