Same again - this time swap space went to zero with sendmail taking most of the CPU and procmail taking 91% of the memory. The mail I received simply said:
From: Cron Daemon <email@example.com>
Subject: Cron <root@server> /usr/bin/mrtg /etc/mrtg/mrtg.cfg --lock-file /var/lock/mrtg/mrtg_l --confcache-file /var/lib/mrtg/mrtg.ok
Date: Tue, 16 Aug 2005 22:08:12 +0100
ERROR: It looks as if you are running two copies of mrtg in parallel on
the same config file. There is a lockfile (/var/lock/mrtg/mrtg_l) and it is
is only 0 seconds old ... Check your crontab.
(/etc/crontab and /var/spool/cron/root)
... and yet there's notthing suspicious in the crontab file - and I don't have a var/spool/cron/root file at all.
procmail is procmail-3.22-16
sendmail is sendmail-8.13.4-2