In my case the cron job is run as user "meriksson" not as root. My crontabs entries located in /var/spool/cron/tabs/meriksson look like this:
# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/tmp/kde-meriksson/kcronKPdxtc.tmp installed on Mon Jun 26 15:07:06 2006)
# (Cron version V5.0 -- $Id: crontab.c,v 1.12 2004/01/23 18:56:42 vixie Exp $)
# E-posta utdatan till specificerat konto.
MAILTO=myaccount@mailprovider.se
# Avast4Home uppdatering
0 7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 * * * /usr/bin/avast-update
# Virusscanning
15 15,20 * * * /home/meriksson/bin/daglig-scan
# This file was written by KCron. Copyright (c) 1999, Gary Meyer
# Although KCron supports most crontab formats, use care when editing.
# Note: Lines beginning with "#\" indicates a disabled task.
The avast-update part works great, the problem is the scan part..
I have now registered avast as root and the /root/.avast/avastrc file was created. I´m sorry to say this didn´t solve my problem