Symptoms:
After performing a vMotion of a virtual machine with a network card in a disconnected state, you experience these symptoms:
Note: A network card is in a disconnected state if the Connection option in the Edit Settings tab of a virtual machine is deselected.
This issue is resolved in VMware vCenter Server 5.5 Update 2d.
To work around this issue when you are unable to upgrade, trigger the creation of a new port by connecting the affected virtual machine to another portgroup and then moving it back to the original portgroup.