It looks like you have two different processes trying to listed on the same port, which is impossible.
Generally, you should always look at IANA port assignments and makes sure that a custom application does not listed on a well-known or registered port unless you are trying to implement some well-known protocol on the server site.
Look at this table:
http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml[
^].
The port 80 is reserved for HTTP. I don't think Visual Studio runs anything on this port (except your application). When you use Visual Studio for ASP.NET or other Web development, during your application run-tome it starts a special "development Web server" on a different port, which is done to avoid disrupting the services using well-known ports. You might have overridden the default, I don't know.
So, review all software which might listen to the port 80 and eliminate the conflict: stop HTTP server is you have one, change port number in configuration or something like that.
To find the ends, you may want to use a
port scanner, please see
http://en.wikipedia.org/wiki/Port_scanner[
^].
—SA
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