Hey,
During the past 3 weeks I had no WiFi on my brand new laptop (which… previously had WiFi running fine).
long story short: updating WiFi drivers while avast internet security is running rendered WLAN service useless (service was stuck from that point on “stopping” and refused to either stop or run) which rendered WiFi non-functional.
solution was: disable all of Avast’s shields and then install the WiFi driver again.
And that was it, painless and swift.
so if any of you get problems with WiFi … just follow the above : )