I had an issue today running a WebApp locally on my own machine. Turns out that Skype uses Port 80 and 443, or that is will use them if it needs to because of firewall issues. To fix this particular issue do the following.
From the Tools menu select Options.
Click on Advanced
Then click on Connections
Uncheck the "Use port 80 and 433 as alternatives"
Quit Skype and reopen it.
This fixed my issue. This may be something you can't do as Skype attempts to use port 80 and 443 to get by firewalls, if your company tries to block programs like Skype.