This thread is Sony VAIO specific, so I think I have an answer that belongs in this thread.
I had lots of trouble with my Sony VAIO FIT15.
The Sony approved intel graphics driver, and the windows update graphics driver will load an old driver which does not work.. Unacceptable @ Sony - Thanks for wasting my time. How hard is it to approve a driver.
You need to manually install the latest intel driver for WiDi to function correctly.
Minimum version is 10.18.10.3345.
I also found Windows Update replaced my manually installed driver with the older driver, and I needed to manually install again.