Many times when you a do a physical to virtual (P2V) migration on a windows machine to a virtual environment like VMware it doesn’t pick up and remove all redundant hardware devices.  Sometimes this circumstance can lead to performance or stability issues for the virtual machine (VM).  Note, this primarily relates to network adapters, see Microsoft KB Q269155.

A good sign that this has happened is if you get the following message when you try to adjust the  TCP/IP settings on you new NICs:

The IP address XXX.XXX.XXX.XXX you have entered for this network adapter is already assigned to another adapter Name of adapter. Name of adapter is hidden from the network and Dial-up Connections folder because it is not physically in the computer or is a legacy adapter that is not working. If the same address is assigned to both adapters and they become active, only one of them will use this address. This may result in incorrect system configuration. Do you want to enter a different IP address for this adapter in the list of IP addresses in the advanced dialog box?

The process to find and remove these devices is pretty easy follow the process below and it will get you on your way

1. Within the VM, start a command prompt, eg: Start => Run => cmd.exe 

2. Type set devmgr_show_nonpresent_devices=1, and then press ENTER.

3. Type devmgmt.msc, and then press ENTER.

4. Within the console that appears click View, and then select Show Hidden Devices.  

5. Expand the Network Adapters tree and uninstall the ghosted devices.