Just in case it catches anyone else out, remove trailing white-space after *User* in configuration files: /etc/clamd.conf /etc/freshclam.conf. The configuration file parser, until version 0.94.2 removed white-space, since version 0.95 it doesn't, so if you run clamd.conf with:
User qscand<whitespace>, it calls getpwnam(filter<whitespace>) and not getpwname(filter).
Reported as bug 1518.
https://wwws.clamav.net/bugzilla/show_bug.cgi?id=1518