If everything was working fine but you had to force Visual Studio to
close, you may be unable to launch the Visual Studio Development Server
because port XXX is in use.
To solve it this problem, open Windows Task Manager and End the following Process
WebDev.WebServer40.EXE
Then restart Visual Studio
Otherwise you may have a conflict with Eset personal security settings.
Click the link below.
http://stackoverflow.com/questions/607562/visual-studio-development-server-using-wrong-port
See also
http://stackoverflow.com/questions/607562/visual-studio-development-server-using-wrong-port