Looks like a debconf issue.
Setting up clamav-base (0.96.1+dfsg-0ubuntu0.10.04.1) ...
Use of uninitialized value $reply in scalar chomp at
/usr/share/perl5/Debconf/FrontEnd/Passthrough.pm line 66.
Use of uninitialized value $reply in concatenation (.) or string at
/usr/share/perl5/Debconf/FrontE
** Attachment added: "AptOrdering.txt"
https://bugs.launchpad.net/bugs/618107/+attachment/1491203/+files/AptOrdering.txt
** Attachment added: "Dependencies.txt"
https://bugs.launchpad.net/bugs/618107/+attachment/1491204/+files/Dependencies.txt
** Attachment added: "Df.txt"
https://bug