This is espeically relevant for installs done via Ubuntu Server (in my case trusty i386)
If you read the page I linked, it shows how the ethernet device names are changed, depending on how they are located in the box.
LOM (Lan-on-Motherboard, devices built onto the motherboard) devices get a device name like emX.
PCI devices get a device name like ethX. (other distributions actually go much further than this, and mix in manufacturer specific names a la BSD).
If you have a LOM device, like I have, on a few machines, then the ethernet device is em1 (not em0), and somewhere in the initrd, a kernel panic happens. (You see this after the IP-Config messages).
removing the biosdevname package, and rebuilding the initrd solves the problem.