Running Visual Studio 2010 Asp.Net web code using the Local IIS Web server Version 7.5 (Windows 7 x64), I came across the error:-
Unable to start debugging on the web server. The server committed a protocol violoation. Section=ResponseStatusLine
The problem exists because
it seems that having skype installed and running can take control of Port 80 which is used as the default port for IIS. Therefore to fix this, make sure you uncheck the "Use port 80 and 443 as alternatives for incoming connections" in Skype - Tools - options - Advanced - Connection.