I recently configured a server running a virtualmin control panel and soon discovered an issue when clients tried to read e-mail. In some cases the mail would never be received by the client, but the mailbox seemed to have content. In addition to this the server was using 100% of CPU for a single clamav process which eventually brought the machine to a halt (lucky it was on a VMware box). To kill the excessive processes you can always:
From a little bit of searching a simple solution was found by editing:
Adding at the base:
deb http://volatile.debian.net/debian-volatile etch/volatile main
Then do the following:
apt-get update apt-get install clamav clamav-base clamav-daemon clamav-data clamav-docs clamav-freshclam
Then remove the line you added (rather comment out) and update the sources again, followed by:
This should reload the AV program and get messages delivered... don't forget to comment out the line in the sources file and the update the packages, otherwise you will potentially replace all packages with volatile versions on next update!