I don't use VMware but am responsible for the network infrastructure it runs on in our data center.
I don't know specifically what version of ESX they are running but on my end the Cisco gear is stacked 3750Gs.
One of the techs from the VMWare group came to me yesterday and said one of the NICs on their farm was plugged in to the wrong port.
It was plugged into g2/0/35 instead of g2/0/36. Both ports have identical programming except for the description. Both ports locked at 1000/full and in VLAN 65.
The issue is when we moved the patch cable from g2/0/35 to g2/0/36 the port wouldn't come up until I set g2/0/36 to auto/auto and then it negotaitaed at 100/full. We moved the patch cable back to g2/0/35 and the everything was fine again, running at a locked 1000/full. We tried this multiple times.
So I started thinking maybe there is a physical issue with g2/0/36. I reconfigured g2/0/36 for 1000/full again and plugged it into a another server and it came online at 1000/full no problem.
So now I am thinking it is something funky with Vmware. I browsed through the VMWare support forums and found similair scenarios but I need something concrete to bring back to the Vmware team tomorow morning.