I've just been through this as well and thought I should leave the solution here for others. It could be due to either Hyper-V blocking the port or this faulty Windows Update.
In my case, it looks like when I installed the Android SDK, it installed the android emulator which uses Hyper-V for hardware acceleration. As @kaloian.petkov mentioned, Hyper-V blocks the port. In the windrunner logs you will see something like:
Failed to bind to port: 0.0.0.0:50051
The nicest way around this is to selectively excludes the port from Hyper-V management by running the following commands in a command prompt (cmd) (started as Administrator).
dism /Online /Disable-Feature:Microsoft-Hyper-V
netsh int ipv4 add excludedportrange protocol=tcp startport=50051 numberofports=1
dism /Online /Enable-Feature:Microsoft-Hyper-V /All
Once rebooted, verify that the port is excluded by running:
netsh interface ipv4 show excludedportrange protocol=tcp
You should see the port as shown below:
Protocol tcp Port Exclusion Ranges
Start Port End Port
---------- --------
50051 50051 *
This should allow the port to be used by windrunner and should not break the rest of your Hyper-V configuration.