For a while now freshclam kept barfing with:

# /usr/bin/freshclam -u clamav -v
ClamAV update process started at Fri Aug 31 18:42:55 2007
WARNING: Your ClamAV installation is OUTDATED!
WARNING: Local version: 0.90.1 Recommended version: 0.91.2
DON'T PANIC! Read http://www.clamav.net/support/faq
main.inc is up to date (version: 44, sigs: 133163, f-level: 20, builder: sven)
Downloading daily-4092.cdiff [100%]
Ignoring mirror 85.25.252.58 (too often connections with outdated version)
ERROR: getpatch: Can't download daily-4093.cdiff from db.de.clamav.net
Ignoring mirror 85.25.252.58 (too often connections with outdated version)
Trying host db.de.clamav.net (194.77.146.139)...
Downloading daily-4093.cdiff [100%]
Ignoring mirror 194.77.146.139 (too often connections with outdated version)

Since we're running Debian/stable, we won't receive any newer clamav version (without pinning and stuff), but the too often connections with outdated version is more serious, since our virus db could not be updated. Searching for this error turned up quite a few results, but nothing related to a particular debian bug. Finally I came accross bug# 606 which contains an actual fix for newer clamav versions and a workaround, for (debian/stable-)users like us:

# sed 's/^ScriptedUpdates.*/ScriptedUpdates no/' -i /etc/clamav/freshclam.conf
# freshclam -u clamav -v
....
# sed 's/^ScriptedUpdates.*/ScriptedUpdates yes/' -i /etc/clamav/freshclam.conf

Now the daily updates should work again. Read why this works.