[Exim] Problem with a cron job and "Message is frozen"

"Message is frozen" now seemingly fills up my /var/log/exim/mainlog
(which is now 80 megabytes, if you think that is normal). Anyways, I
get around 5 of them a second, and exim takes up 100 % of the CPU at the
time. This happens only when this script is run:
# /etc/cron.d/exim: crontab fragment for exim

# Run queue every 30 minutes
08,38 *     * * *     mail   if [ -x /usr/sbin/exim -a -f /etc/exim.conf
]; then /usr/sbin/exim -q >/dev/null 2>&1; fi

and exim -Mvh message-id shows that it belongs to postmaster, so I
assumed it was an
/etc/aliases problem, but I've tried tweaking it to the best of my
ability to no avail.

Is there a way to allow this cron job to run without pushing my load
averages up to 50?

This is a weird occurrance that just started happening recently, if
anyone has any clue about
the cause, I'd appreciate input =).

Jonathan Hseu