I'm afraid that there is nothing to do with the network card.
When you are using Virtualization software such as VMWare and the likes, you must be sure that the server doesn't work in bridged mode. This VMs cannot send packets to the real network as our switches are configured to block the machine if the MAC address of the packets sent from it is not the same physical MAC address registered.
You can find more information about it in the following guides:
http://help.ovh.com/VMware
and the section about network configuration.
That's regarless of if you are using IP failovers or not on those VMs.
Cheers, guys!