Remove NetworkManager

[Xen]

> Don't know if this helps but here is the networking section from my
> Ubuntu Server 14.04 setup notes:-

Aye, I did not realize the binary of NetworkManager was still running 
and it was probably causing those problems, as always.

They created a system where you have to tell it when not to interfere, 
instead of a system that asks you when it can interfere.

This "negative" approach creates all the problems...

Anyway, thank you for your message, very kind.

> auto lo
> iface lo inet loopback
> auto eth0
> iface eth0 inet dhcp

> This file was last edited on my server on 2015-04-30 and gives me no
> problems, but maybe other "features" get in the way on a desktop
> system.
> 
> Dave