Include/SkypeHTTPConflict

From wiki.visual-prolog.com

Skype (potentially) conflicts with HTTP/HTTPS servers, because Skype (by default) reserves port 80 (HTTP) and 443 (HTTPS).

As a result you cannot run an HTTP/HTTPS server when Skype runs (in default mode).

The solution is to turn off port 80/443 in Skype.

See this video: Handling port conflicts with Skype on Windows