Unpacking extlinux (from .../extlinux_2%3a4.05+dfsg-6_i386.deb) ...
Processing triggers for man-db ...
Setting up extlinux (2:4.05+dfsg-6) ...
P: Checking for EXTLINUX directory... found.
P: Writing config for /boot/vmlinuz-3.5.0-25-generic...
P: Writing config for /boot/vmlinuz-3.5.0-24-generic...
P: Writing config for /boot/vmlinuz-3.5.0-23-generic...
P: Writing config for /boot/vmlinuz-3.5.0-22-generic...
P: Writing config for /boot/vmlinuz-3.5.0-21-generic...
P: Writing config for /boot/vmlinuz-3.5.0-19-generic...
P: Writing config for /boot/vmlinuz-3.5.0-18-generic...
P: Writing config for /boot/vmlinuz-3.5.0-17-generic...
P: Writing config for /boot/vmlinuz-3.4.0-030400-generic...
P: Updating /boot/extlinux/linux.cfg...
E: /usr/share/syslinux/themes/debian/extlinux: No such file or directory
dpkg: error processing extlinux (--configure):
 subprocess installed post-installation script returned error exit status 1