Have you installed a third-party instance of ClamAV through your system package manager or via source instead of through the "Manage Plugins" option in Web Host Manager?
Did you first remove any manual installation of ClamAV (installed either through source or RPM)? Check to see the file ownership of "/var/log/clamav/freshclam.log":
Code:
ls -al /var/log/clamav/freshclam.log
I've seen cases where it's owned by "clam" instead of "clamav" after an unsupported ClamAV installation.