Upgrade to 12.1: error generating initrd

Upgrading with “zypper dup” failed at reboot due to the absence of /boot/initrd-3.1.0-1.2.1-desktop. Checking the installation log I found this:

Installing: kernel-desktop-3.1.0-1.2.1 [done]
Additional rpm output:

Kernel image: /boot/vmlinuz-3.1.0-1.2-desktop
Initrd image: /boot/initrd-3.1.0-1.2-desktop
Root device: /dev/sda1 (mounted on / as ext3)
Resume device: /dev/loop0
Fatal storage error. Device /dev/loop0 does not have a driver.
There was an error generating the initrd (1)

Don’t understand the meaning of “/dev/loop0 does not have a driver” and thus do not know how to solve this. Help would be very much appreciated.

Why is this in the Multimedia subforum? I do not see any connection with music, movie, pictures, …
How many music/video lovers do you you think, that know what initrd is?

Looks something for the Install/Boot/Login one to me.