I have seen in two Windows 7 SP1 machines in the past 2 weeks that have a problem I could not figure out.
For some reason, each machine would suddenly indicate that the"This copy of windows is not genuine", even though it clearly is and licensed through our KMS.
One thing I did notice is the the Plug and Play service was missing on each machine and none of the network interfaces were displayed in device manager or the command prompt.
I ran sfc /scannow and showed nothing wrong.
Ran every malware/virus scanner I can get my hands on, nothing found.
The only thing in common was that they both were infected with a trojan about a week earlier.
My only option was to reimage the machine and all was well.