Credits to Walter Haidinger:

Small, but annoying bug in grml-1.1:
The network is shut down _before_ the filesystems are unmounted.

Perhaps no problem when running from CD but I boot grml over PXE
from NFS (from http://wiki.grml.org/doku.php?id=terminalserver).

Obviously shutdown hangs when grml tries to unmount the NFS root
filesystem without a network...