[Grml] My DHCP client isn't started automatically anymore

[Hermann]

Hi,
since a safe-upgrade on 08.10.09, dhclient3 does not start automatically
anymore.
I use a router )Fritzbox), which is connected via USB to my machine. The
hardware gets detected properly, and I have activated DHCP on the
Fritzbox.
The internal IP has not changed.
Reconfiguring the network via grml-config results in turning on the
client, but specifying the startup of dhclient at boot, fails.
Although I answer this question with "yes", the client doesn't start
with the boot procedure. The config script exits with code 1 shown at the
prompt, but there are no error messages on the screen.
The only thing that works is to include the networking script into the
startup procedure by:
update-rc.d networking defaults
This was not necessary before.
The client's binary has the date of 05.10.09, although the problems came
up yesterday.
I include the contents of my /etc/network/interfaces here:

auto lo eth0
iface lo inet loopback
iface eth0 inet dhcp

Any hints?
Hermann