If you’re here that means you’re probably having problems with MS VS 2005 R2.
I have a Broadcome NetXtreme GbE NIC (only one). Unlike blog posts found in top Google searches, my case didn’t involve any change of configuration that I know of. It just stopped working one day. I therefore used a less invasive approach:
a) Update the Broadcom GbE driver (broadcom.com)
b) Uninstall VM Network Services
c) Reboot the box and install VM Network Services again.
This worked for me. Maybe b & c alone would have sufficed.