As I am working completely remotely these days I have found my use of Skype increase. This is mainly for chatting to my co-dev throughout the day. Not being a massive Skype fan I actually have it configured for use through Trillian which is quite a good multi-protocol IM client.
Today while mid call with my co-dev I found my Firefox instance hanging and so did an iisreset on my local dev box. Killed Firefox and attempted to start debugging again. Only Visual Studio didn't want to play ball. It showed an error dialog with the following message :
Unable to start debugging on the web server. The server committed a protocol violation. Section=ResponseStatusLine.
OK, that was a new one to me! I started to dig about and found that the caused of the problem was Skype. It appears that Skype will try and use ports 80 and 443 as optional ports to connect on. This meant that IIS was not able to listen to either of these ports.
I killed Trillian (which in turned killed Skype) and all was resolved and I could debug again.
It appears you can disable the option to listen to these ports in Skype. You need to go to :
Tools -> Options -> Advanced -> Connection
On this option page you need to uncheck "Use port 80 and 443 as alternatives for incoming connections". Restart Skype and you should find you have no more issues.