change it to clamav and try to restart the service.
On my dansguardians, it's working.
# Run as another user (clamd must be started by root for this option to work)
# Default: don't drop privileges
User clamav
# Initialize supplementary group access (clamd must be started by root).
# Default: no
AllowSupplementaryGroups yes
[2.0.1-RELEASE][root@xxxxxx]/root/.ssh(13): freshclam
ClamAV update process started at Mon Aug 6 17:24:07 2012
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Local version: 0.97.3 Recommended version: 0.97.5
DON'T PANIC! Read http://www.clamav.net/support/faq
main.cvd is up to date (version: 54, sigs: 1044387, f-level: 60, builder: sven)
Downloading daily-15222.cdiff [100%]
Downloading daily-15223.cdiff [100%]
Downloading daily-15224.cdiff [100%]
Downloading daily-15225.cdiff [100%]
Downloading daily-15226.cdiff [100%]
daily.cld updated (version: 15226, sigs: 250065, f-level: 63, builder: ccordes)
bytecode.cld is up to date (version: 188, sigs: 38, f-level: 63, builder: neo)
Database updated (1294490 signatures) from database.clamav.net (IP: 64.22.33.90)
Clamd successfully notified about the update.