.. on my system freshclam.log has:
Ownership (chown) smelog:smelog
Perms (chmod) 644
Run
ps -efa | grep fresh
to see if there is another freshclam thread running but frozen/stuck.
If so use
killall freshclam
to get rid of it and then try running freshclam manually.
I have just had a prob with an SME 6.x box and freshclam where the mirrors weren't sync'd when it tried to update, just be patient with this one or edit the freshclam.conf file to point to a mirror that is up to date (not recommended unless you REALLY need it)
HTH