How to resolve the problem when Ubuntu on VMWare cannot get the ip address.

Ubuntu 3.8.0 64-bit installed on VMWare 9 could not get the ip address.

Network is configured as DHCP in Ubuntu and the bridge mode is set on VMWare VM configuration.
At first run, it worked and even samba service with Windows 7, the host OS worked successfully.

Today it does not work at all and no ip address is acquired when I checked with 'ifconfig' command.
Shutting down and restarting the VM was not the solution.

Googling told me the answer.

Set the /etc/network/interfaces file as follows.
============================
auto eth0
iface eth0 inet dhcp
============================

There was "lo" instead of "eth0".
Still I don't understand why it worked before and now I have to change the above file.

In some linux, the file is /etc/networking/interfaces, the google told.

Thanks, Google.