dhcp problem on ethernet card

[Luca Ferrari]

Hi,
I'm using kubuntu 7.04 but my dhcp client is no more working. This is what 
happens: the computer boots, then the knetworkmanager keep the gear running 
but no address is provided to my host. After a few minutes, if I manually 
configure the ethernet card I'm able to use the network, thus the card is 
running.

In the /var/log/messages I found:
dhcdbd: message_handler: message handler not found under /com/redhat/dhcp/eth0 
for sub-path eth0.dbus.get.reason

while if I manually try to restart the networking (/etc/init.d/networking 
restart) I get:

Can't allocate interface ethlease {
  interface .
Failed to bring up eth0.

Please note that the /etc/network/interfaces file contains:

iface eth0 inet dhcp

Any idea about that?

Thanks,
Luca