RTNETLINK problem after insert some parameters in editing physical interface.

Hi all,

After chaging my furniture and unplug cables I lost my 1GB connection. I have not solved my problem yet but I got one greater.
I added some extra values in field option when I tried to revocover 1GB network connection. Now I only get my network address when I type:

dhclient eth0

Also when I restart network or I started up the system I get:

Configuring network interfaces...RTNETLINK answers: File exists
Failed to bring up lo.
done.

Could anyone help me on that?

PS. Thanks Volker for the marvelous system. 2 year in a row no great problem so far

Here is the output for cat /etc/network/interfaces

# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet6 loopback


# eth0 network interface
auto eth0
allow-hotplug eth0
iface eth1 inet manual
    address 192.xxx.xxx.xxx
   netmask 255.255.255.0
  network 192.xxx.xxx.xxx
 gateway 192.xxx.xxx.xxx
    pre-down ip -4 addr flush dev eth0
    mtu 1500
   pre-up ethtool -s $IFACE
    post-up /sbin/ifconfig $IFACE mtu 1500
   pre-up ethtool -s $IFACE
iface eth0 inet6 manual
    pre-down ip -6 addr flush dev eth0

Tks.