I don't usually ask for help so directly, usually google have all i need but this time i'm seriously lost. Hope you can help me .s

The thing is, i have a server with Vmware ESXi 4.1 and 5 already running and configured virtual servers, but whenever i try to make a new one on CentOS 6.X it leaves me without eth0 to be activated in any way. When installing CentOS, in the screen of localhost.localdomain i try by the button in the left down corner of the screen to make eth0 connect automatically but it tells me a NetworkManager Error: cannot start eth0. So...in command line once the CentOS is already installed, i have configured ifcfg-eth0 and manually tried to take up the eth0 but when i restart network service "Bringing up eth0: Failed" and sometimes even "shutting down eth0: Failed"

Thanks in advance