the init script suggested at http://mmonit.com/wiki/Monit/Upstart generates a lot of false positives on quad-core workstations, with ubuntu, at shutdown...
It looks like monit is trying to recover processes (sshd, ntpd, etc) as the machine is shutting down. With 800 workstations... it's no funny at the end of the day.
I would suggest that the "stop line" is changed to:
stop on starting rc RUNLEVEL=
as one can find on other corners of the Internet ,o)