I am experiencing the same issue on several VMs. 3 of the Guests were built from OVM Templates and 2 of the other machines were built from scratch.
OS: Windows 2008 R2 SP1 and Windows 7 SP1
Verified that the Ghost NICs were gone.
Cleared TCP Stack with the netsh winsock reset and the netsh interface IPV4 reset commands
After 7-10 reboots the Guest will get an IP of 169.254.34.203 (Duplicate) and the IPV4 address will also show as (Duplicate)
ESXi Version: 5.1 update 3
vNIC VMXNET3
I have tried removing the vNICs, rebooting, running the set_devmgr_show_nonpresent_devices=1, start devmgmt.msc, show hidden devices, and removed the vNICs, rebooted, and then readded a vNIC and set the Static IP address. I then rebooted the machine 7 times and then it failed again.
At this point I am at a loss.