After another reboot I notice an error on the startup:
starting venet0 failed to start
It was trying to get DHCP information, but no IP was given to the machine, it's suppose to be like this.
So I googled and googled but no answer.
I decided to take a look at the /etc/sysconfig/network-scripts/ifcfg-venet0 and the setup command line of CentOS messed it up..
so here is how the file should look for venet0:
DEVICE=venet0ONBOOT=yesSTARTMODE='onboot'
A reboot and all was working again...