Can you try deleting the network adapter and re add it. Do it first with a test virtual machine.
No luck. When I remove the network adapter then re-add it, I do not have an option to select that portgroup anymore. The strange part is that its works fine until I attempt to edit the VM as it will auto select a different portgroup. It complains that the portgroup is not available but it actually works fine.
I had a similar issue, check here:
UI lets you pick an existing portgroup when creating a vmkernel nic, even one with VMs attached to it, giving strange results for the VMs.
So make sure you haven't accidentally converted your VM Port group into a vmkernel port group.
sorry about the long delay getting back to you (new born at home and configuring my sever/lab is far down the list). This was exactly my problem. I created a new port group for my VMK adapter, the messages went away.