Comment 2 for bug 1233081

It seems the system ran out of ram during the install:

update-initramfs: deferring update (hook will be called later)
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.8.0-31-generic /boot/vmlinuz-3.8.0-31-generic
run-parts: executing /etc/kernel/postinst.d/dkms 3.8.0-31-generic /boot/vmlinuz-3.8.0-31-generic
/usr/sbin/dkms: fork: Cannot allocate memory
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.8.0-31-generic /boot/vmlinuz-3.8.0-31-generic
Killed
run-parts: /etc/kernel/postinst.d/initramfs-tools exited with return code 137
Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/linux-image-3.8.0-31-generic.postinst line 1010.
dpkg: error processing linux-image-3.8.0-31-generic (--configure):
 subprocess installed post-installation script returned error exit status 2